A Practical Handbook on the Distillation of Alcohol from Farm Products
by F. B. Wright · English · Gutenberg #46377 · 436,727 chars · public domain (US)
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Title: A Practical Handbook on the Distillation of Alcohol from Farm Products
Author: F. B. Wright
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*** START OF THE PROJECT GUTENBERG EBOOK A PRACTICAL HANDBOOK ON THE DISTILLATION OF ALCOHOL FROM FARM PRODUCTS ***
A PRACTICAL HANDBOOK
ON THE
DISTILLATION OF ALCOHOL
FROM
FARM PRODUCTS
INCLUDING
The Processes of Malting; Mashing and Mascerating; Fermenting
and Distilling Alcohol from Grain, Beets,
Potatoes, Molasses, etc., with Chapters
on Alcoholometry and the
DE-NATURING OF ALCOHOL
FOR USE IN
Farm Engines, Automobiles, Launch Motors, and in Heating
and Lighting; with a Synopsis of the New Free
Alcohol Law and its Amendment and the
Government Regulations.
BY F. B. WRIGHT.
SECOND EDITION, REVISED AND GREATLY ENLARGED
NEW YORK
SPON & CHAMBERLAIN, 123 LIBERTY STREET
LONDON
E. & F. N. SPON, LIMITED, 57 HAYMARKET, S.W.
1907
Copyright, 1906,
By SPON & CHAMBERLAIN.
Copyright, 1907,
By SPON & CHAMBERLAIN.
McIlroy & Emmet, Printers, 22 Thames St., New York, U. S. A.
PREFACE TO SECOND EDITION.
Since the passage of the "Free Alcohol Act" there has been a constantly
increasing demand for information as to the manufacture of industrial
alcohol. This, with the favorable reception accorded to the first edition
of this book has lead the publishers to bring out a second edition.
The entire volume has been carefully revised and not only has the
original text been amplified but new chapters have been added explaining
the most modern and approved methods and appliances both as used in
Europe and in this country. Another valuable feature of the present
volume is the collection of U. S. de-naturing formulas covering the
special denaturants necessitated by the various arts and by the
Government requirements. The chapters on modern distilling apparatus
rectifiers and modern plants have been very carefully prepared in order
to give the reader a clear idea of the various types of apparatus in use
to-day and of their general place in a distillery system. The value of
the book has been further increased by numerous additional illustrations.
It would be impossible in the compass of one small volume to describe all
the practical details of alcohol manufacture particularly as these
details vary with every distillery, but it has been the aim of the author
to give sufficient information to enable every reader to understand the
theory and general practice of the art, leading him from the simple
methods and apparatus used until the last ten years to the more
complicated stills and processes which have been lately devised.
Inasmuch as the manufacture of industrial alcohol has been most highly
perfected in France and Germany, use has been made of the best European
authorities and in particular the author begs to acknowledge his
indebtedness to Sa Majeste L'Alcohol by L. Beaudry de Saunier. The
publishers' and author's acknowledgements are also due to the Vulcan
Copper Works Company of Cincinnati, Ohio, and to the Geo. L. Squier
Manufacturing Company, Buffalo, New York, for their kindness in allowing
illustrations to be given of modern American distilling apparatus.
F. B. WRIGHT.
New York, Aug. 1, 1907.
PREFACE.
To the majority of persons Alcohol connotes liquor. That it is used to
some extent in the arts, that it is a fuel, is also common knowledge, but
Alcohol as a source of power, as a substitute for gasoline, petroleum,
and kindred hydrocarbons was hardly known to the generality of Americans
until the passage of the "De-naturing Act" by the last Congress.
Then Alcohol leaped at once into fame,--not merely as the humble servant
of the pocket lamp, nor as the Demon Rum, but as a substitute for all the
various forms of cheap hydrocarbon fuels, and as a new farm product, a
new means for turning the farmer's grain, fruit, potatoes, etc., into
that greatest of all Powers, _Money_.
That Alcohol was capable of this work was no new discovery accomplished
by the fiat of Congress, but the Act of June 7, 1906, freed de-natured
Alcohol from the disability it had previously labored under,--namely, the
high internal revenue tax, and so cheapened its cost that it could be
economically used for purposes in the arts and manufactures which the
former tax forbade.
This Act then opens the door of a new market to the farmer and the
manufacturer, and it is in answer to the increased desire for
information as to the source of Alcohol and its preparation that this
book has been written. The processes described are thoroughly reliable
and are such as have the approval of experience.
As was stated above, Alcohol is not a natural product, but is formed by
the decomposition of sugar or glucose through fermentation. This leaves
Alcohol mixed with water, and these in turn are separated by
distillation.
The literature treating of the distillation of Alcohol from farm products
is very scant. But due credit is here given to the following foreign
works which have been referred to: Spon's EncyclopÊdia of the Industrial
Arts, which also contains an article on Wood Alcohol, Mr. Bayley's
excellent Pocketbook for Chemists, and Mr. Noel Deerr's fine work on
Sugar and Sugar Cane.
NEW YORK,
Oct. 31, 1906
CONTENTS.
CHAPTER I.
ALCOHOL, ITS VARIOUS FORMS AND SOURCES.
Its chemical structure. How produced. Boiling points. Alcohol
and water. Alcohol, where found. Produced from decomposition of
vegetables. Sources. Principal alcohols. 1
CHAPTER II.
THE PREPARATION OF MASHES, AND FERMENTATION.
A synopsis of steps. Mashing starchy materials. Gelatinizing
apparatus and processes. Saccharifying. Cooling the mash.
Fermentation. Yeast and its preparation. Varieties of
fermentation:--Alcoholic, acetous, lactic and viscous. Fermenting
periods. Fermenting apparatus and rooms. Strengthening alcoholic
liquors. 8
CHAPTER III.
DISTILLING APPARATUS.
The simple still. Adams still. Concentrating stills. Compound
distillation. Dorn's still. Continuous distillation. The
Cellier-Blumenthal still. Coffey's still. Current stills.
Regulating distillery fire. 33
CHAPTER IV.
MODERN DISTILLING APPARATUS.
The principles of modern compound stills. Vapor traps and their
construction. Steam regulation. Feed regulation. American
apparatus. The Guillaume inclined column still. 66
CHAPTER V.
RECTIFICATION.
General principles of "fractionation." Old form of rectifying
still. Simple fractionating apparatus. "Vulcan" rectifier.
Barbet's twin column rectifier. Guillaume's "Agricultural"
rectifying apparatus. Rectifying by filtration. 82
CHAPTER VI.
MALTING.
The best barley to use. Washing. Steeping. Germinating. The "wet
couch." The "floors." "Long malt." Drying. Grinding and crushing. 103
CHAPTER VII.
ALCOHOL FROM POTATOES.
Washing. Gelatinizing and saccharifying. Low pressure steaming,
and apparatus therefor. Crushing the potatoes. High pressure
steaming and apparatus. The vacuum cooker. The Henze steamer.
Isolation of starch without steam. English methods. Saccharifying
the starch. 110
CHAPTER VIII.
ALCOHOL FROM GRAIN, CORN, WHEAT, RICE, AND OTHER CEREALS.
Relative yields of various cereals. Choice of grain. Proportions
of starch, etc., in various grains. Grinding. Steeping.
Preparatory mashing. Saccharifying. Treatment of grain under high
pressure. Softening grain by acid. 126
CHAPTER IX.
ALCOHOL FROM BEETS.
Beet cultivation. Composition. Soil and manures. Sowing.
Harvesting. Storing. Production of alcohol from beets. Cleaning
and rasping. Extraction by pressure. Extraction by maceration
and diffusion. The diffusion battery. Fermentation. Direct
distillation of roots. 140
CHAPTER X.
ALCOHOL FROM MOLASSES AND SUGAR CANE.
The necessary qualities in molasses. Beet sugar. Molasses mixing
and diluting. Neutralizing the wash. Pitching temperature.
Distilling. Fermenting raw sugar. Cane sugar molasses. "Dunder."
Clarifying. Fermenting. Various processes. 163
CHAPTER XI.
ALCOHOLOMETRY.
Hydrometers in general. Proof spirit. Syke's hydrometer.
Gay-Lussac's hydrometer. Tralles alcoholometer. Hydrometric
methods. Estimation of alcohol. Field's alcoholometer. Grisler's
method and apparatus. Estimating sugar in mash. Determination of
alcoholic fruits. Physical tests. Chemical tests. The Permanganate
of Potash test. Results by Barbet. 174
CHAPTER XII.
DISTILLING PLANTS, THEIR GENERAL ARRANGEMENT AND EQUIPMENT.
Simple apparatus. Elaborate plants. Steam stills. The fermenting
room. Ventilation. Fermenting vats. Preparatory vats. Arrangement
of grain distillery. A small beet distillery. Large beet
distilling plant. Transporting beets. Potato distillery. Molasses
distillery. Fermenting house for molasses. Transportation of
molasses to distillery. Coal consumption. 189
CHAPTER XIII.
DE-NATURED ALCOHOL, AND DE-NATURING FORMUL∆.
Uses of alcohol. De-natured spirit:--Its use in Germany, France
and England. The "De-naturing Act." The uses of de-natured
alcohol. Methods and FormulÊ for de-naturing. De-natured alcohol
in the industrial world. 211
CHAPTER XIV.
DE-NATURING REGULATIONS IN THE UNITED STATES.
The Free Alcohol Act of 1906, and proposed changes therein. The
Amendment of 1907. Internal Revenue Regulations. 224
Index. 261
LIST OF ILLUSTRATIONS
No. PAGE.
1 Vacuum mash cooker _to face_ 10
2 Henze steamer 12
3 Mash cooler, air system 15
4 Mash cooler, water system 17
5 Yeasting and fermenting apparatus _to face_ 22
6 A simple still 34
7 Simple direct-heated still 35
8 Simple still, with rectifier 37
9 Adam's still 39
10 Corty's simplified distilling apparatus 41
11 Double still 42
12 Dorn's compound still 43
13 Compound still 46
14 Compound direct-fire still 47
15 Cellier-Blumenthal still 49
16 Details of rectifier column 50
17 Details of condenser and mash heater 52
18 Coffey's rectifying still 55
19, 20 Rotary current still 59, 60
21 Indicator for regulating the distilling fire 61
22 Diagrammatic view of column still and accessory
apparatus _to face_ 64
23 Distilling plate 64
24, 25 Barbet traps 68
26 Steam regulator 70
27 Gauge glass for regulator 72
28 Continuous distilling apparatus with external tubular
condenser _to face_ 72
29 Detail of chamber, continuous still 73
30, 31 Details of perforated plate _A_ 75, 76
32 Continuous distilling apparatus with goose separator _to face_ 76
33 Section of Gillaume's inclined column still 78
34 Gillaume's inclined column still 79
35 Rectifying still 88
36 Section of rectifying still 89
37 Fractional distilling apparatus 91
38 Rectifying apparatus with external tubular condenser _to face_ 94
39 Twin column Barbet rectifier 95
40 Gillaume's rectifier and inclined still 97
41 Steaming vat for potatoes 112
42 Bottom of steaming vat 113
43 Steam generator 114
44 Potato steamer and crusher 116
45 Bohn's steamer and crusher 118
46 Stack for storing beets 148
47 Storage cellar for beets 149
48 Beet and potato rasp 152
49 Dujardin's roll press 155
50 Defusion battery 158
51 Mixing vat 165
52 Syke's hydrometer 176
53 Field's alcoholometer 182
54 Geisler's apparatus 184
55 Continuous grain alcohol distillery--Barbet's system 198
56 Grain distillery, capacity 2500 bushels per day _to face_ 198
57 Small beet distillery 200
58 Large beet distillery 202
59 Molasses distillery, capacity 2500 gallons per day _to face_ 206
60 Molasses fermenting house 207
CHAPTER I.
ALCOHOL, ITS VARIOUS FORMS AND SOURCES.
=Alcohol.= (Fr., _alcool_; Ger., _alkohol_.) Formula, C_{2}H_{6}O.
Pure alcohol is a liquid substance, composed of carbon, hydrogen, and
oxygen, in the following proportions:
C 52.17
H 13.04
O 34.79
------
100.00
It is the most important member of an important series of organic
compounds, all of which resemble each other closely, and possess many
analogous properties. They are classed by the chemist under the generic
title of "Alcohols."
Alcohol does not occur in nature; it is the product of the decomposition
of sugar, or, more properly, of _glucose_, which, under the influence of
certain organic, nitrogenous substances, called _ferments_ is split up
into alcohol and carbonic anhydride. The latter is evolved in the form of
gas, alcohol remaining behind mixed with water, from which it is
separated by distillation. The necessary purification is effected in a
variety of ways.
TABLE I.--THE BOILING POINTS OF ALCOHOLIC LIQUORS OF DIFFERENT
STRENGTHS, AND THE PROPORTIONS OF ALCOHOL IN THE VAPORS GIVEN OFF.
===========+===========+===========+===========+===========+===========
Proportion| |Proportion |Proportion | |Proportion
of alcohol|Temperature|of alcohol |of alcohol |Temperature|of alcohol
in the | of the |in the | in the | of the | in the
boiling | boiling |condensed | boiling | boiling |condensed
liquid in | liquid. |vapor in | liquid in | liquid. | vapor in
100 vols. | |100 vols. | 100 vols. | | 100 vols.
-----------+-----------+-----------+-----------+-----------+-----------
92 | 171.0 F. | 93 | 20 | 189.5 F. | 71
90 | 171.5 F. | 92 | 18 | 191.6 F. | 68
85 | 172.0 F. | 91.5 | 15 | 194.0 F. | 66
80 | 172.7 F. | 90.5 | 12 | 196.1 F. | 61
75 | 173.6 F. | 90 | 10 | 198.5 F. | 55
70 | 175.0 F. | 89 | 7 | 200.6 F. | 50
65 | 176.0 F. | 87 | 5 | 203.0 F. | 42
50 | 178.1 F. | 85 | 3 | 205.1 F. | 36
40 | 180.5 F. | 82 | 2 | 207.5 F. | 28
35 | 182.6 F. | 80 | 1 | 209.9 F. | 13
30 | 185.0 F. | 78 | 0 | 212.0 F. | 0
25 | 187.1 F. | 76 | | |
===========+===========+===========+===========+===========+===========
Pure, absolute alcohol is a colorless, mobile, very volatile liquid,
having a hot, burning taste, and a pungent and somewhat agreeable odor.
It is very inflammable, burning in the air with a bluish-yellow flame,
evolving much heat, leaving no residue, and forming vapors of carbonic
anhydride and water. Its specific gravity at 0∞ C (32∞ F.) is .8095, and
at 15.5∞ C. (60∞ F.) .794; that of its vapor is 1.613. It boils at 78.4∞
C. (173∞ F.). The boiling point of its aqueous mixtures are raised in
proportion to the quantity of water present. Mixtures of alcohol and
water when boiled give off at first a vapor rich in alcohol, and
containing but little aqueous vapor; if the ebullition be continued a
point is ultimately reached when all the alcohol has been driven off and
nothing but pure water remains. Thus, by repeated distillations alcohol
may be obtained from its mixtures with water in an almost anhydrous
state.
Absolute alcohol has a strong affinity for water. It absorbes moisture
from the air rapidly, and thereby becomes gradually weaker; it should
therefore be kept in tightly-stoppered bottles. When brought into contact
with animal tissues, it deprives them of the water necessary for their
constitution, and acts in this way as an energetic poison. Considerable
heat is disengaged when alcohol and water are brought together; if,
however, ice be substituted for water, heat is absorbed, owing to the
immediate and rapid conversion of the ice into the liquid state. When one
part of snow is mixed with two parts of alcohol, a temperature as low as
5.8∞ F. below zero is reached.
When alcohol and water are mixed together the resulting liquid occupies,
after agitation, a less volume than the sum of the two original liquids.
This contraction is greatest when the mixture is made in the proportion
of 52.3 volumes of alcohol and 47.7 volumes of water, the result being,
instead of 100 volumes, 96.35. A careful examination of the liquid when
it is being agitated reveals a vast number of minute air-bubbles, which
are discharged from every point of the mixture. This is due to the fact
that gases which are held in solution by the alcohol and water separately
are less soluble when the two are brought together; and the contraction
described above is the natural result of the disengagement of such
dissolved gases. The following table represents the contraction undergone
by different mixtures of absolute alcohol and water.
TABLE II.--100 VOLUMES OF MIXTURE AT 59∞ F.
========+============++========+============++========+============
Alcohol.|Contraction.||Alcohol.|Contraction.||Alcohol.|Contraction.
--------+------------++--------+------------++--------+------------
100 | 0.00 || 65 | 3.61 || 30 | 2.72
95 | 1.18 || 60 | 3.73 || 25 | 2.24
90 | 1.94 || 55 | 3.77 || 20 | 1.72
85 | 2.47 || 50 | 3.74 || 15 | 1.20
80 | 2.87 || 45 | 3.64 || 10 | 0.72
75 | 3.19 || 40 | 3.44 || 5 | 0.31
70 | 3.44 || 35 | 3.14 || |
========+============++========+============++========+============
Alcohol is termed "absolute" when it has been deprived of every trace of
water, and when its composition is exactly expressed by its chemical
formula. To obtain it in this state it must be subjected to a series of
delicate operations in the laboratory, which it would be impossible to
perform on an industrial scale. In commerce it is known only in a state
of greater or less dilution.
Alcohol possesses the power of dissolving a large number of substances
insoluble in water and acids, such as many inorganic salts, phosphorus,
sulphur, iodine, resins, essential oils, fats, coloring matters, etc. It
precipitates albumen, gelatine, starch, gum, and other substances from
their solutions. These properties render it an invaluable agent in the
hands of the chemist.
Alcohol is found in, and may be obtained from, all substances--vegetable
or other--which contain sugar. As stated above, it does not exist in
these in the natural state, but is the product of the decomposition by
fermentation of the saccharine principle contained therein; this
decomposition yields the spirit in a very dilute state, but it is readily
separated from the water with which it is mixed by processes of
distillation, which will subsequently be described. The amount of alcohol
which may be obtained from the different unfermented substances which
yield it varies considerably, depending entirely upon the quantity of
sugar which they contain.
Alcohol is produced either from raw materials containing starch, as
potatoes, corn, barley, etc., or raw materials containing sugar, as
grapes, beets, sugar-cane, etc.
The following are some of the most important sources from which alcohol
is obtained: Grapes, apricots, cherries, peaches, currents, gooseberries,
raspberries, strawberries, figs, plums, bananas, and many tropical
fruits, artichokes, potatoes, carrots, turnips, beet-root, sweet corn,
rice and other grains. Sugar-cane refuse, sorgum, molasses, wood, paper,
and by a new French process from acetylene. On a large scale alcohol is
usually obtained from sugar beets, molasses or the starch contained in
potatoes, corn and other grains. The starch is converted into maltose by
mixing with an infusion of malt. The maltose is then fermented by yeast.
Sulphuric acid may be used to convert even woody fibre, paper, linen,
etc., into glucose, which may in turn be converted into alcohol.
TABLE III.--PRINCIPAL ALCOHOLS.
=================+=======================+==============+==============
Chemical Name. | Source. | Formula. |Boiling Point
∞F.
-----------------+-----------------------+--------------+--------------
1 Methyl Alcohol|Distillation of Wood |CH_{3}OH | 150.8
2 Ethyl " |Fermentation of sugar |C_{2}H_{5}OH | 172.4
3 Propyl " | " " grapes |C_{3}H_{7}OH | 206.6
4 Butyl " | " " beets |C_{4}H_{9}OH | 242.6
5 Amyl " | " " potatoes|C_{5}H_{11}OH | 278.6
6 Caproyl " | " " grapes |C_{6}H_{13}OH | 314.6
7 Aenanthyl " |Distillation castor oil|C_{7}H_{15}OH | 347.
| with potatoes | |
8 Capryl " |Essential oil hog weed |C_{8}H_{17}OH | 375.8
9 Nonyl " |Nonane from petroleum |C_{9}H_{19}OH |
10 Rutyl " |Oil of Rue |C_{10}H_{21}OH|
11 Cytyl " |Spermaceti |C_{16}H_{33}OH|
12 Ceryl " |Chinese wax |C_{26}H_{53}OH|
13 Melisyl " |Bees' wax |C_{30}H_{61}OH|
=================+=======================+==============+==============
Among a variety of other substances which have been and are still used
for the production of alcohol in smaller quantities, are roots of many
kinds, such as those of asphodel, madder, etc. Seeds and nuts have been
made to yield it. It will thus be seen that the sources of this
substance are practically innumerable; anything, in fact, which contains
or can be converted into sugar is what is termed "alcoholisable."
Alcohol has become a substance of such prime necessity in the arts and
manufactures, and in one form or another enter so largely into the
composition of the common beverages consumed by all classes of people
that its manufacture must, of necessity, rank among the most important
industries of this and other lands.
Of the alcohols given in the above table only two concern the ordinary
distiller, or producer of alcohol for general use in the arts. Methyl
alcohol, the ordinary "wood alcohol," or wood naphtha, and Ethyl alcohol,
which is produced by the fermentation of sugar and may therefore be made
from anything which contains sugar.
Ethyl alcohol forms the subject of this treatise. Aside from its chemical
use in the arts as a source of energy and as a fuel, alcohol will likely
soon compete with petroleum, gasoline, kerosene, etc., under the Act of
Congress freeing the "de-naturized" spirit from the Internal Revenue tax.
This act and the de-naturing process are covered in the last chapters of
this book.
CHAPTER II.
THE PREPARATION OF MASHES, AND FERMENTATION.
Alcohol may be produced either from, (1) farinacious materials, such as
potatoes or grains, (2), from sacchariferous substances such as grapes,
sugar beets, sugar cane, or the molasses produced in sugar manufacture.
THE PREPARATION OF STARCHY MATERIALS.
=Saccharification.= =Preparatory Mashing.= With starchy materials it is
first necessary to convert the starch into a sugar from which alcohol can
be produced by the process of fermentation. This is called
saccharification.
=Gelatinizing.= The first step in this process is gelatinizing the
starch;--that is, forming it into a paste by heating it with water, or
into a liquid mass by steaming it under high pressure. The liquid or
semi-liquid mass is then run into a preparatory mash vat and cooled.
=Saccharifying.= The disintegrated raw materials or gelatinized starch in
the preparatory mash vat is now to be "saccharified" or converted into
sugar. This is effected by allowing malt to act on the starch. This malt
contains a certain chemical "ferment" or enzyme, called "diastase" ("I
separate").
This is able under proper conditions to break up the gelatinized starch
into simpler substances--the dextrins--and later into a fermentable sugar
called maltose.
=Fermentation.=--The maltose or sugar in the "mash" is now to be
converted into alcohol. This is accomplished by fermentation, a process
of decomposition which converts the sugar into carbonic acid and alcohol.
Fermentation is started by yeast, a fungus growth, which in the course of
its life history produces a matter called zymose which chemically acts on
the sugar to split it up into carbonic acid gas and alcohol.
Yeast may be either "wild" or cultivated. If the mash is left to stand
under proper condition the wild yeast spores in the air, will soon settle
in the mash and begin to multiply. This method of fermentation is bad
because other organisms than yeast will also be developed,--organisms
antagonistic to proper fermentation. As a consequence, pure or cultivated
yeast is alone used.
This yeast is cultivated from a mother bed in a special yeast mash and
when ripened is mixed with the mash in the fermenting vat. At a
temperature between 50∞ F. and 86∞ F. the yeast induces fermentation,
converting the sugar of the mash into carbon dioxid which escapes, and
alcohol which remains in the decomposed mash, or "beer" as it is termed
in the United States.
It now remains to separate the alcohol from the water of the beer with
which it is mixed. This is accomplished by distillation and
rectification, as will be fully described in the chapters following.
PRODUCTION OF ALCOHOL FROM SACCHARIFEROUS SUBSTANCES.
Substances such as grape juice, fruit juice, sugar beets, cane sugar and
molasses already contain fermentable sugar. Saccharification is therefore
not needed and juices or liquids from these matters are either directly
fermented as in the case of sugar cane, or--as in the case of sugar
beets--the sugar in juice is transferred by yeast into a fermentable
sugar.
MASHING STARCHY MATERIALS.
We will now consider in more detail the preparation of mashes from
starch-containing substances.
=Gelatinizing Apparatus.= These comprise either ordinary vats, into which
steam at low pressure is admitted (see Fig. 44), cookers and stirrers
such as shown in Fig. 1 and 45 or the Henze steamer (Fig. 2.)
[Illustration: FIG. 1.--Vacuum Mash Cooker. (_To face page 10_)]
An example of a cooking and mashing apparatus and its connections is
shown in Fig. 1. This is the vacuum cooker put on the market by the
Vulcan Copper Works Company, of Cincinnati, Ohio. This consists of a
cylindrical steel vessel the interior of which is fitted with stirrer
arms attached to a shaft making about sixty revolutions per minute. The
steam enters the vessel at the bottom by means of pipes conducting it
from a manifold, or header, in the same manner as is shown in the
apparatus illustrated in Fig. 45. Attached to each pipe at its point of
entrance is a check valve to spray the steam through the mash. A
thermometer for registering the temperature and a water gauge are placed
in the manifold. The grain enters the cooker from the grain hopper by way
of a spout. The cylinder has been previously supplied with hot water and
during the mixing of the meal with the hot water the mass is constantly
stirred. The malt is mixed with water in the small grain tub which is
provided with a stirrer. The malt mash is admitted into the cooker and
the mass thoroughly mixed by the arms. After the mashing, the product
passes off to the drop tub and from thence to the mash coolers where it
is cooled to the proper temperature for fermentation. The gearing for
agitating the malt mash and the grain or potato mash is evident from the
drawing.
The pressure steamers used in mashing are shown in Fig. 2. They comprise
a cylindrical vessel preferably conical or partly conical, provided with
steam entrance pipes, air valves and a manhole. At the bottom of the cone
forming the lower end of the steamer is a grating located in an exit
pipe provided with a valve. One of the steam entrance pipes is so located
that the steam is forced in at the top of the cylinder while the other
allows steam to enter at the bottom of the cylinder. The device is
provided with a pressure gauge and an air cock.
[Illustration: FIG. 2.--Henze Steamer.]
In use the body of the apparatus is partly filled with water and the
material to be treated. This is acted upon by a steam pressure of two
atmospheres, which is later increased to three, steam entering by the
lowermost pipe, passing up through the water and potatoes thoroughly
agitating the same and passing away by the steam gauge. After standing at
the last pressure for ten or fifteen minutes the lower steam inlet is
closed; the upper inlet and the blow-out valve are opened. The steam is
then increased to its highest point or about four atmospheres and the
lower valve is opened. The disintegrated material is forced out by the
steam through the grating at the bottom of the cone. This comminutes it
and pulps it before it passes into the preparatory mash tub. Blowing out
requires about 40 to 50 minutes. Steaming and blowing out together cover
a space of two hours. The pressure of the steam before blowing out should
be such that the steam is constantly being blown off through the safety
valve. Thus the mass in the steamer is agitated and the material entirely
disintegrated and gelatinized.
=Process.= Into these apparatuses the potatoes and corn or grain first
ground into mash, or even corn or grain unground, if the pressure is high
enough, are disintegrated and cooked by steam under high pressure. During
this process the starch becomes partially dissolved and partially
gelatinized, which occurs when a pressure of some 65 pounds has been
attained, with a temperature of about 300∞ F.
=Saccharifying.= It is now necessary to saccharify the gelatinized mass.
This is accomplished by adding to it a certain amount of malt, whereby
maltose or sugar is formed through the action of the diastase. The amount
of maltose so created is in proportion to the amount of malt used, the
length of time it is acting, the dilution of the mash, and the existence
of a proper temperature. The temperature best fitted for this action lies
above 122∞ F., but in order to entirely dissolve the starch a temperature
of 145∞ F. should be used. In addition, at this higher temperature, the
bacteria inimical to fermentation are destroyed. A higher temperature
than 145∞ F. should not be allowed, except in extraordinary cases as it
injures the effectiveness of the diastase.
=Apparatus.= The mixture of the malt with the mash may either take place
in the heater and cooker itself (see Fig. 2) or in a preparatory mash
vat.
In the first instance, the malt is allowed to enter the cooking cylinder
when the temperature of the mash is about 145∞ F. The mash is stirred
until thoroughly mixed when the product is drawn into a receptacle called
a drop tub and later reduced to a proper fermenting temperature.
When the Henze type of steamer is used, the pulped mass (see Page 121) is
blown into a preparatory mash vat, at the proper temperature. It is left
to stand at this temperature for a period varying from twenty minutes to
an hour and a half.
=Cooling the Mash.= Saccharification takes place at a temperature above
122∞ F., but the proper fermenting temperature is only about 63∞ F. to
68∞ F., and hence some means must be adopted for cooling the hot mash to
this temperature and for so cooling it in a relatively short time.
[Illustration: FIG. 3.--Mash Cooler, Air System.]
=Cooling= may be accomplished by submitting the mash to currents of air;
to contact with cold water coils or by the use of ice. One of the
simplest coolers of the first class is shown in Fig. 3.
This consists of a shallow panlike tank A having means for introducing
and drawing off the mash. Rotating in the center of the tank is a
vertical shaft _C_ carrying radiating stirrer arms _B_. Braces _M_
extend to the middle of these arms and the arms carry a number of blades
or paddles _b_, which extend down into the mash. Above the arms, mounted
loosely on the same shaft, but rotating in the opposite direction, are
fans _H_ supported by arms _J_ which create air currents over the
agitated mash. These fans move at a much faster rate than the stirrers
_B_.
A simple form of driving gear is shown. The main shaft _C_ is rotated by
a large bevel gear _D_, meshing with a small pinion _E_ on the end of a
driving shaft _F_, which is driven by a belt. This shaft also carries a
bevel gear _L_, which meshes with a bevel gear _K_ mounted on a sleeve.
This sleeve surrounds and rotates freely on the central shaft _C_, being
supported at its lower end in ball bearings _m m_, mounted on the shaft.
This combination gives opposite rotation to the faces and stirrer arms
and at different speeds. The driving mechanism can be of course varied.
Another simple method of air cooling would be to let the mash run down a
series of enclosed steps or chutes, the casing being kept cool by an air
blast. Mashes may be even cooled by mere stirring by paddles, but this
takes a long time and much labor.
The preparatory mash vats used to-day are almost all provided with
stirrers formed of hollow blades capable of a rapid stirring movement
through the mash. Through the hollow blades cold water is forced. Mash
vats of this kind should have the following qualities. They should be
strongly built, particularly as regards the stirrers so as to be used
with thick mashes. They should thoroughly and uniformly stir and mix the
mash and they should be capable of cooling the mash within an hour, and
should be so constructed as to be easily cleaned.
By using coils of pipe which may be inserted or withdrawn from the mash
tub, and through which cold water is forced, the mash may be effectively
cooled, but the best plan for quick cooling is to bring a comparatively
thin layer of the mash in contact with the coils. This may be
conveniently done by using a system of comparatively large water pipes
enclosing small pipes for the passage of the mash.
[Illustration: FIG. 4.--Mash Cooler, Water System.]
This should be arranged in a stand like the coils of a radiator with an
incline from the inlet end of the top pipe to the outlet end of the
lowermost pipe. As stated, the small pipe carries the mash, the large
pipe the water.
Preferably the mash flows downward while the water is forced upward in a
contrary direction by means of a pump or a high level reservoir. The
cooled mash should flow into the fermenting tank at a temperature of
about 68∞ F.
There are many varieties of mash cooling apparatuses on the market of
more or less complication suited to the needs of large and expensive
plants.
The form of cooler best to be used depends upon the circumstances of each
case and whether thick or thin mashes are to be distilled. The cooler
should, however, be capable of thorough cleansing so that no portion of
one mashing be carried to another.
=Fermentation= is an obscure and seemingly spontaneous change or
decomposition which takes place in most vegetable and animal substances
when exposed at ordinary temperatures to air and moisture. While
fermentation broadly covers decay or putrifaction, yet it is limited in
ordinary use to the process for producing alcoholic liquors from
sacchariferous mashes.
Fermentation is brought about by certain bodies called ferments--these
are either organized, as vegetable ferments such as yeast, or unorganized
as diastase--the enzyme of germinated malt. The last is used to convert
starch into maltose, the first is used to convert maltose into
fermentable sugar. The organized ferments are either to be found floating
freely in the air under the name of wild yeast or are artificially
produced. If a solution of pure sugar be allowed to stand so that it can
be acted on by the organisms in the air, it will remain unaltered for a
long time, but finally mold will appear upon it and it will become sour
and dark-colored. If, however, a suitable ferment is added to it, such as
yeast, it rapidly passes into a state of active fermentation by which the
sugar is split up into alcohol and carbon dioxid, the process continuing
from 48 hours to several weeks according to the temperature, the amount
of sugar present, and the nature and quantity of the ferment.
Fermentation cannot occur at a temperature much below 40∞ F., nor above
140∞ F. The limits of practical temperature, however, are 41∞ to 86∞ F.
Brewer's yeast is chiefly employed in spirit manufacture.
The most striking phenomena of fermentation are the turbidity of the
liquid, the rising of gas bubbles to the surface, and the increase in
temperature, the disappearance of the sugar, the appearance of alcohol
and the clearing of the liquid. At the end a slight scum is formed on the
top of the liquid and a light colored deposit at the bottom. This deposit
consists of yeast which is capable of exciting the vinous fermentation in
other solutions of sugar. The lower the temperature the slower the
process, while at a temperature above 86∞ F. the vinous fermentation is
liable to pass into other forms of fermentation to be hereafter
considered.
There are many theories of fermentation, of which the two most important
are those of Pasteur and Buchner. The first teaches that fermentation is
caused purely by the organic life of the yeast plant and is not a mere
chemical action, whereas the second view most largely held to-day is that
fermentation is a purely chemical change due to certain unorganized
substances called "enzymes" present in the yeast.
The theory need not detain us. It is sufficient that the yeast plant in
some manner acts to decompose the saccharified mash into alcohol and
carbonic acid gas.
=Yeast= is a fungus, a mono-cellular organism, which under proper
conditions propogates itself to an enormous extent. There are many races
or varieties of yeast each having its peculiar method of growth.
For our purposes we may divide the yeast races into two classes, wild
yeast and cultivated yeast. Originally any of the yeast races were
supposed to be good enough to effect fermentation but to-day every effort
is made to procure and use only those races which have the greatest power
to decompose sugar. It was for this reason that the old distiller kept
portions of his yeast over from one fermentation to the next. This was
yeast whose action they understood and whose abilities were proven. This
yeast so kept was open, however, to the chance of contamination and yeast
to-day is as carefully selected and bred as is a strain of horses, or
dogs, or plants.
After getting a portion of selected pure yeast for breeding purposes, it
may be sowed, that is, propagated very carefully in a yeast mash, in
sterilizing apparatus, where all chance of contamination by bacteria or
wild yeast is avoided. From this bed of mother yeast, or start yeast, the
yeast for the successive yeast mashes is taken.
The preparation of the various varieties of yeast mashes is too lengthy
to be set forth except in special treatises on the subject, but the
ordinary method of yeasting is as follows, reference being made to Fig.
5, which shows the apparatus used in the yeasting and fermenting
departments of a distillery, as installed by the Vulcan Copper Works, of
Cincinnati. The yeast tubs are shown to the left of the illustration.
They are each provided with cooling coils and stirrers.
The yeast mash we will assume is composed of equal parts of barley malt
and rye meal. Hot water at 166∞ F. is first put into the mash tub. The
rake or stirrers are then rotated and the meal run in slowly. The
stirring is continued for twenty minutes after the meal is all in, during
which the mash has become saccharified.
The mash is then allowed to stand for about twenty hours, and to grow
sour by lactic fermentation. The lactic acid so produced protects the
mother yeast from infection by suppressing wild yeast and bacteria.
During this period great care is taken to prevent the temperature of the
mash falling below 95∞ F. and consequent butyric and acetous fermentation
following. After it has so stood the sour mash is cooled by circulating
water in the coils and stirring until it is reduced to from 59∞ to 68∞ F.
depending on whether the mash is thin or thick. Start yeast during the
cooling of the mash when at above 86∞ F. is added and stirred in. For the
next twelve hours the yeast ferments and when a temperature of 84∞ F. has
been attained the mash is cooled to 65∞ F. at which temperature it is
maintained until allowed to enter the fermenting tubs through the pipe
leading thereto from the yeast tub.
There are four principal kinds of fermentation: alcoholic, acetous,
lactic and viscous.
=Alcoholic Fermentation.= This may be briefly described as follows: The
mash in the fermenting vat having been brought to the proper temperature,
the ferment is thrown in, and the whole is well stirred together.
This is known as pitching.
[Illustration: FIG. 5.--Yeasting and Fermenting Apparatus.
(_To face page 22_)]
The proper pitching temperature varies with the method of fermentation
adopted, the length of the fermenting period, the materials of the mash,
its thickness or attenuation. It must always be remembered that there is
a great increase in the temperature of the "beer" during fermentation and
that the temperature at its highest should never under any circumstances,
become greater than 86∞ F. and with thick mashes that even a less heat is
desirable. Therefore the pitching temperature should be such that the
inevitable rise due to fermentation shall not carry the temperature to or
beyond the maximum point desired for the particular mash being
treated. It is to accurately control the pitching temperature and the
fermenting temperature that the fermenting tanks are provided with
cooling appliances.
In about three hours' time, the commencement of the fermentation is
announced by small bubbles of gas which appear on the surface of the vat,
and collect around the edges. As these increase in number, the whole
contents are gradually thrown into a state of motion, resembling violent
ebullition, by the tumultuous disengagement of carbonic anhydride. The
liquor rises in temperature and becomes covered with froth. At this
point, the vat must be covered tightly, the excess of gas finding an exit
through holes in the lid; care must now be taken to prevent the
temperature from rising too high, and also to prevent the action from
becoming too energetic, thereby causing the contents of the vat to
overflow. In about twenty-four hours the action begins to subside, and
the temperature falls to that of the surrounding atmosphere. An hour or
two later, the process is complete; the bubbles disappear, and the
liquor, which now possesses the characteristic odor and taste of alcohol,
settles out perfectly clear. The whole operation, as here described,
usually occupies from forty-eight to seventy-two hours. The duration of
the process is influenced, of course, by many circumstances, chiefly by
bulk of the liquor, its richness in sugar, the quality of the ferment,
and the temperature.
=Acetous Fermentation.= This perplexing occurrence cannot be too
carefully guarded against. It results when the fermenting liquor is
exposed to the air. When this is the case, the liquor absorbs a portion
of the oxygen, which unites with the alcohol, thus converting it into
acetic acid as rapidly as it is formed. When acetous fermentation begins,
the liquor becomes turbid, and a long, stringy substance appears, which
after a time settles down to the bottom of the vat. It is then found that
all the alcohol has been decomposed, and that an equivalent quantity of
acetous acid remains instead. It has been discovered that the presence of
a ferment and a temperature of 68∞ to 95∞ F. are indispensable to acetous
fermentation, as well as contact with the atmosphere. Hence, in order to
prevent its occurrence, it is necessary not only to exclude the air, but
also to guard against too high a temperature and the use of too much
ferment. The latter invariably tends to excite acetous fermentation. It
should also be remarked that it is well to cleanse the vats and utensils
carefully with lime water before using, in order to neutralize any acid
which they may contain; for the least trace of acid in the vat has a
tendency to accelerate the conversion of alcohol into vinegar. A variety
of other circumstances are favorable to acetification, such as the use of
a stagnant or impure water, and the foul odors which arise from the vats;
stormy weather or thunder will also engender it.
=Lactic Fermentation.= Under the influence of lactic fermentation, sugar
and starch are converted into lactic acid. When it has once begun, it
develops rapidly, and soon decomposes a large quantity of glucose; but as
it can proceed only in a neutral liquor, the presence of the acid itself
speedily checks its own formation. Then, however, another ferment is
liable to act upon the lactic acid already formed, converting it into
_butyric acid_, which is easily recognized by its odor of rank butter.
Carbonic anhydride and hydrogen are evolved by this reaction. The latter
gas acts powerfully upon glucose, converting it into a species of gum
called _mannite_, so that lactic fermentation--in itself an intolerable
nuisance--becomes the source of a new and equally objectionable waste of
sugar. It can be avoided only by keeping the vats thoroughly clean; they
should be washed with water acidulated with five per cent of sulphuric
acid. An altered ferment, or the use of too small a quantity, will tend
to bring it about.
The best preventives are _thorough cleanliness_, and the use of good,
fresh yeast in the correct proportion.
=Viscous Fermentation.= This is usually the result of allowing the vats
to stand too long before fermentation begins. It is characterized by the
formation of viscous or mucilaginous matters, which render the liquor
turbid, and by the evolution of carbonic anhydride and hydrogen gases the
latter acting as in the case of lactic fermentation and converting the
glucose into mannite. Viscous fermentation may generally be attributed to
the too feeble action of the ferment. It occurs principally in the
fermentation of white wines, beer, and beet-juice, or of other liquors
containing much nitrogenous matter. It may be avoided by the same
precautions as are indicated for the prevention of lactic fermentation.
=Periods of Fermentation.= The operation of fermentation may be
conveniently divided into three equal periods.
The first or pre-fermentation period is that when the yeast mixed into
the mash is growing; the temperature should then be kept at about 63 to
68∞ F. during which time the yeast is propagated. The growth of the yeast
is manifested by the development of carbonic acid gas and by a slight
motion of the mash. When alcohol is produced to an extent of say five per
cent. the growth of the yeast stops.
The second period of chief fermentation then begins. Carbonic acid is
freely developed and the sugar is converted into alcohol. The temperature
at this time should not exceed 81.5∞ F. The second period of fermentation
continues about 12 hours, when the last period commences.
During the third period or after fermentation there is a lessening of the
formation of carbonic acid and a lowering of the temperature. In this
stage the mash is kept at a temperature of 77∞ to 81∞ F.
In order to conveniently regulate the temperature of the mash the vat may
be provided with a copper worm at the bottom thereof, through which cold
water is forced. This, however, need only be used for thick mashes. There
are also various kinds of movable coolers used for this purpose.
There are a number of different forms which fermentation may take. The
insoluble constituents of the mash in the process of fermentation are
forced to the surface, and form what may be termed a cover. If the
carbonic acid gas bubbles seldom break this cover it indicates that the
conversion of the sugar into alcohol and carbonic acid is proceeding very
slowly and imperfectly. If, however, the cover is swirling and seething,
and particularly if the cover is rising and falling with every now and
then a discharge of gas, it is an indication that the conversion is
properly proceeding. Foaming of the mash is to be prevented, as the froth
or foam flows over the mash tank and considerable loss is sustained. It
may be prevented by pouring a little hot lard into the vat, or petroleum,
provided its odor will not interfere with the use of the alcohol when
distilled.
Water is added in small quantities near the termination of the second
period of fermentation. This dilutes the alcohol, in the mash and lessens
its percentage, and thus the further growth of the yeast is permitted.
After fermentation the mash takes either the form of a thick diluted pulp
or of a thin liquor. Again the reader is reminded that the mash after
fermentation contains alcohol mixed with water--and that the next step in
the process--distillation is necessary merely to separate the alcohol
from the water.
There is always some loss in the process of fermentation; in other words,
the actual production is below the theoretical amount due. Theoretically
one pound of starch should yield 11.45 fluid ounces of alcohol. With a
good result 88.3 per cent. of this theoretical yield is obtained; with an
average result of 80.2 per cent. and with a bad result only about 72.6
per cent. or less.
=Fermenting Apparatus.= It remains now to describe briefly the vessels or
vats employed in the processes of fermentation. They are made of oak or
cypress, firmly bound together with iron bands, and they should be
somewhat deeper than wide, and slightly conical, so as to present as
small a surface as possible to the action of the air. Their dimensions
vary, of course, with the nature and quantity of the liquor to be
fermented. Circular vats are preferable to square ones, as being better
adapted to retain the heat of their contents. The lid should close
securely, and a portion of it should be made to open without uncovering
the whole. For the purpose of heating or cooling the contents when
necessary, it is of great advantage to have a copper coil at the bottom
of the vat, connected with two pipes, one supplying steam and the other
cold water.
=Iron vats= have also been used, having a jacketed space around them,
into which hot or cold water may be introduced. As wooden vats are porous
and hence uncleanly they have to be constantly scrubbed and disinfected.
It is advisable to cover the interior with linseed oil, varnish or with a
shellac varnish. The diameter of the coil varies according to the size of
the vat.
=The room= in which the vats are placed should be made as free from
draughts as possible by dispensing with superfluous doors and windows; it
should not be too high and should be enclosed by thick walls in order to
keep in the heat. As uniformity of temperature is highly desirable, a
thermometer should be kept in the room, and there should be stoves for
supplying heat in case it be required. The temperature should be kept
between 64∞ F. and 68∞ F.
Every precaution must be taken to ensure the most absolute cleanliness;
the floors should be swept or washed with water daily, and the vats, as
pointed out above, must be cleaned out as soon as the contents are
removed. For washing the vats, lime-water should be used when the
fermentation has been too energetic or has shown a tendency to become
acid; water acidulated with sulphuric acid is used when the action has
been feeble and the fermented liquor contains a small quantity of
undecomposed sugar. Care must be taken to get rid of carbonic anhydride
formed during the operation. Buckets of lime-water are sometimes placed
about the room for the purpose of absorbing this gas; but the best way of
getting rid of it is to have a number of holes, three or four inches
square, in the floor, through which the gas escapes by reason of its
weight. The dangerous action of this gas and its effects upon animal life
when unmixed with air are too well know to necessitate any further
enforcement of these precautions.
=The beer= obtained by mashing and fermenting consist essentially of
volatile substances, such as water, alcohol, essential oils and a little
acetic acid, and of non-volatile substances, such as cellulose, dextrine,
unaltered sugar and starch, mineral matters, lactic acid, etc.
=The volatile constituents= of the liquor possess widely different
degrees of volatility; the alcohol has the lowest boiling point, water
the next, then acetic acid, and last the essential oils. It will thus be
seen that the separation of the volatile and non-volatile constituents by
evaporation and condensation of the vapors given off is very easily
effected, and that also by the same process, which is termed
_distillation_, the volatile substances may be separated from one
another. As the acetic acid and essential oils are present only in very
small quantities, they will not require much consideration.
The aim of distillation is to separate as completely as possible the
alcohol from the water which dilutes it. Table I shows the amount of
alcohol contained in the vapors given off from alcoholic liquids of
different strength, and also their boiling points.
A glance at this table shows to what an extent an alcoholic liquor may be
strengthened by distillation, and how the quantity of spirit in the
distillate increases in proportion as that contained in the original
liquor diminishes. It will also be seen that successive distillations of
spirituous liquors will ultimately yield a spirit of very high strength.
As an example, suppose that a liquid containing five per cent, of alcohol
is to be distilled. Its vapor condensed gives a distillate containing 42
per cent. of alcohol which, if re-distilled, affords another containing
82 per cent. This, subjected again to distillation, yields alcohol of
over 90 per cent. in strength. Thus three successive distillations have
strengthened the liquor from five per cent. to 90 per cent.
It will thus be clear that the richness in alcohol of the vapors given
off from boiling alcoholic liquids is not a constant quantity, but that
it necessarily diminishes as the ebullition is continued. For example a
liquor containing seven per cent. of alcohol yields, on boiling a vapor
containing 50 per cent. The first portion of the distillate will,
therefore, be of this strength. But as the vapor is proportionally richer
in alcohol, the boiling liquor must become gradually weaker, and, in
consequence, must yield weaker vapors. Thus, when the proportion of
alcohol in the boiling liquid has sunk to five per cent., the vapors
condensed at that time will contain only 40 per cent.; at two per cent.
of alcohol in the liquor, the vapors yield only 28 per cent., and at one
per cent., they will be found when condensed to contain only 13 per cent.
From this it will be understood that if the distillation be stopped at
any given point before the complete volatilization of all the alcohol the
distillate obtained will be considerably stronger than if the process had
been carried on to the end. Moreover, another advantage derived from
checking the process before the end, and keeping the last portions of the
distillate separate from the rest, besides that of obtaining a stronger
spirit, is that a much purer one is obtained also. The volatile,
essential oils, mentioned above, are soluble only in strong alcohol, and
insoluble in its aqueous solutions. They distill also at a much higher
temperature than alcohol, and so are found only among the last products
of the distillation, which results from raising the temperature of the
boiling liquid. This system of checking the distillation and removing the
products at different points is frequently employed in the practice of
rectification.
CHAPTER III.
DISTILLING APPARATUS.
=The Apparatus= employed in the process of distillation is called a
_still_, and is of almost infinite variety. A still may be any vessel
which will hold and permit fermentated "wash" or "beer" to be boiled
therein, and which will collect the vapors arising from the surface of
the boiling liquid and transmit them to a condenser. The still may be
either heated by the direct application of fire, or the liquid in the
still raised to the boiling point by the injection of steam. The steam or
vapor rising from the boiling liquid must be cooled and condensed. This
is done by leading it into tubes surrounded by cold water or the "cold
mash."
The very simplest form of still is shown in Fig. 6, and consists of two
essential parts, the still, or boiler _A_, made of tinned copper, the
condenser _C_ which may be made of metal or wood and the worm _B_ made of
a coil of tinned copper pipe.
The liquor is boiled in _A_ and the vapors pass off into the worm _B_,
which is surrounded by the cold water of the condenser, the distillate
being drawn off at _f_.
The heated vapors passing through the worm _B_ will soon heat up the
water in _C_ thereby retarding perfect condensation. To prevent this, a
cold water supply pipe may be connected to the bottom of _C_ making a
connection at the top of _C_ for an over flow of the warmed up water. By
this means the lowest part of the worm will be kept sufficiently cool to
make a rapid condensation of the vapors.
[Illustration: FIG. 6.--A Simple Still.]
The boiler _A_ can be made in two parts; the upper part fitting into the
lower part snugly at _d_. The pipe from the upper part fitting the worm
snugly at _e_. This will enable the operator to thoroughly cleanse the
boiler before putting in a new lot of liquor. The joints at _e_ and _d_
should be luted with dough formed by mixing the flour with a small
portion of salt and moistening with water. This is thoroughly packed at
the junctions of the parts to prevent the escape of steam or vapor.
Fig. 7 shows such a Still as manufactured by the Geo. L. Squier Mfg. Co.,
Buffalo, N. Y.
[Illustration: FIG. 7.--Simple Direct-Heated Still.]
In an apparatus of this kind, the vapors of alcohol and water are
condensed together. But if instead of filling the condenser _C_ with cold
water, it is kept at a temperature of 176∞ F. the greater part of the
water-vapor will be condensed while the alcohol, which boils at 172.4∞ F.
passes through the coil uncondensed. If therefore the water be condensed
and collected separately in this manner, and the alcoholic vapors be
conducted into another cooler kept at temperature below 172.4∞ F., the
alcohol will be obtained in a much higher state of concentration than it
would be by a process of simple distillation.
Supposing, again, that vapors containing but a small quantity of alcohol
are brought into contact with an alcoholic liquid of lower temperature
than the vapors themselves, and in very small quantity, the vapor of
water will be partly condensed, so that the remainder will be richer in
alcohol than it was previously. But the water, in condensing, converts
into vapor a portion of the spirit contained in the liquid interposed, so
that the uncondensed vapors passing away are still further enriched by
this means. Here, then, are the results obtained; the alcoholic vapors
are strengthened, firstly, by the removal of a portion of the water
wherewith they were mixed; and then by the admixture with them of the
vaporized spirit placed in the condenser. By the employment of some such
method as this, a very satisfactory yield of spirit may be obtained, both
with regard to quality, as it is extremely concentrated, and to the cost
of production, since the simple condensation of the water is made use of
to convert the spirit into vapor without the necessity of having recourse
to fuel. The construction of every variety of distilling apparatus now in
use is based upon the above principles.
A sectional view of another simple form of still is shown in Fig. 8; _V_
is a wooden vat having a tight fitting cover _a_, through the center of
which a hole has been cut. The wide end of a goose neck of copper pipe
_g_ is securely fitted over this aperture, the smaller end of this pipe
passes through the cover of the retort _R_ extending nearly to the
bottom; _f_ is the steam supply pipe from boiler; _M_ the rectifier
consisting of a cylindrical copper vessel containing a number of small
vertical pipes surrounded by a cold water jacket; _o_ the inlet for the
cold water which circulates around these small pipes, discharging at _n_;
the pipes in _M_ have a common connection to a pipe _p_, which connects
the rectifier with coil in cooler _C_; _s_ is a pipe to the receptacle
for receiving the distillate; _u_ cold water supply pipe to cooler, and
_W_ discharge for warmed-up water, _k_ discharge for refuse wash in vat
_V_.
[Illustration: FIG. 8.--Simple Still, with Rectifier.]
The operation is as follows: The vat _V_ is nearly filled with fermented
mash and retort _R_ with weak distillate from a previous operation. Steam
is then turned into the pipe _f_ discharging near the bottom of the vat
_V_ and working up through the mash. This heats up the mash and the
vapors escape up _g_ over into _R_ where they warm up the weak
distillate. The vapors thus enriched rise into _M_, where a good
percentage of the water vapor is distilled, that is, condensed by the
cold water surrounding the small pipes. The vapor then passes over
through _p_ into the coil, where it is liquified and from whence it
passes by pipe _s_ into the receiver. The cold water for cooling both _M_
and _C_ can be turned on as soon as the apparatus has become thoroughly
heated up.
The stills in use to-day in many parts of the South for the production of
whiskey are quite as simple as those above described, and some for the
making of "moonshine" liquor are more so.
The first distilling apparatus for the production of strong alcohol on an
industrial scale was invented by Edward Adam, in the year 1801. The
arrangement is shown in Fig. 9, in which _A_ is a still to contain the
liquor placed over a suitable heater. The vapors were conducted by a tube
into the egg-shaped vessel _B_, the tube reaching nearly to the bottom;
they then passed out by another tube into a second egg _C_; then, in some
cases, into a third, not shown in the figure, and finally into the worm
_D_, and through a cock at _G_ into the receiver. The liquor condensed in
the first egg is stronger than that in the still, while that found in the
second and third is stronger than either. The spirit which is condensed
at the bottom of the worm is of a very high degree of strength. At the
bottom of each of the eggs, there is a tube connected with the still, by
which the concentrated liquors may be run back into _A_ for
redistillation after the refuse liquor from the first distill has been
run off.
[Illustration: FIG. 9.--Adam's Still.]
In the tube is a stop-cock _a_, by regulating which, enough liquor could
be kept in the eggs to cover the lower ends of the entrance pipes, so
that the alcoholic vapors were not only deprived of water by the cooling
which they underwent in passing through the eggs, but were also mixed
with fresh spirit obtained from the vaporization of the liquid remaining
in the bottom of the eggs, in the manner already described.
Adam's arrangement fulfilled, therefore, the two conditions necessary for
the production of strong spirit inexpensively; but unfortunately it had
also serious defects. The temperature of the egg could not be maintained
at a constant standard, and the bubbling of the vapors through the liquor
inside created too high a pressure. It was, however, a source of great
profit to its inventor for a long period, although it gave rise to many
imitations and improvements.
The operation of distilling is often carried on in the apparatus
represented in Fig. 22. It is termed the Patent Simplified Distilling
Apparatus; it was originally invented by Corty, but it has since
undergone much improvement. _A_ is the body of the still, into which the
wash is put; _B_ the head of the still; _c c c_ three copper plates
fitted in the upper part of the three boxes; these are kept cool by a
supply of water from the pipe _E_, which is distributed on the top of the
boxes by means of the pipes _G G G_. The least pure portion of the
ascending vapors is condensed as it reaches the lowest plate, and falls
back, and the next portion as it reaches the second plate, while the
purest and lightest vapors pass over the goose-neck, and are condensed in
the worm. The temperature of the plates is regulated by altering the flow
of water by means of the cock _F_. For the purpose of cleaning the
apparatus, a jet of steam or water may be introduced at _a_. A regulator
is affixed at the screw-joint _H_, at the lower end of the worm, which
addition is considered an important part of the improvement. The part of
the apparatus marked _I_ becomes filled soon after the operation has
commenced; the end of the other pipe _K_ is immersed in water in the
vessel _L_. The advantage claimed for this apparatus is that the
condensation proceeds in a partial vacuum, and that there is therefore a
great saving in fuel. One of these stills, having a capacity of 400
gallons, is said to work off four or five charges during a day of 12
hours, furnishing a spirit 35 per cent. over-proof.
[Illustration: FIG. 10.--Corty's Simplified Distilling Apparatus.]
Fig. 11 represents a double still which was at one time largely employed
in the colonies. It is simply an addition of the common still _A_ to the
patent still _B_. From time to time the contents of _B_ are run off into
_A_, those of _A_ being drawn off as dunder, the spirit from _A_ passing
over into _B_. Both stills are heated by the same fire; and it is said
that much fine spirit can be obtained by their use at the expense of a
very inconsiderable amount of fuel.
[Illustration: FIG. 11.--Double Still.]
=Compound Distillation.= Where stills of the form shown in Figs. 6 and 8
are used the alcohol obtained is weak. Hence it is necessary that the
distillate be again itself distilled, the operation being repeated a
number of times. In the better class of still, however, compound
distillation is performed the mash is heated by the hot vapors rising
from the still and the vapors are condensed and run back into the still
greatly enriched.
[Illustration: FIG. 12.--Dorn's Compound Still.]
The principle of compound distillation is well shown in Dorn's apparatus,
Fig. 12. This consists of a still or boiler _A_ having a large
dome-shaped head, on the interior faces of which the alcoholic vapors
will condense. Thus only enriched vapors will pass up through goose-neck
_B_ to the mash heater _D_. _C_ is a worm the end of which passes out to
a compartment _E_ through an inclined partition _F_. From the compartment
_E_ a pipe _e_ leads into the still _A_. An agitator _H_ is used for
stirring the mash, so that it may be uniformly heated. A pipe _d_
provided with a cock allows the mash to be drawn off into the still _A_.
From the highest point of the compartment _E_ a pipe _M_ leads to
condensing coil _K_ in a tub _J_ of cold water, having a draw-off cock
_I_.
At the exit end of the condensing worm _K_ the tube is bent in a U form
as at _L_, one arm of which has a curved open-ended continuation _n_,
through which the air in the worm is expelled. The other arm opens into
an inverted jar _l_ containing a hydrometer, for indicating the strength
of the spirit. The spirits pass off through _m_ into a receiver.
In operation the mash is admitted into the heater _D_ through _G_ until
the heating tank is nearly filled. A certain amount of mash is then
allowed to run into the still _A_ through the pipe _d_. The cock in _d_
is closed and the fire lighted.
The vapors from the still are condensed in worm _C_ and the condensed
liquid drops down into compartment _E_. Any vapor passing through _B_ and
_C_ so highly heated as to be uncondensed in coils _C_ passes through
the layer of liquid in compartment _E_, collects in the highest portion
of the compartment and passes through pipe _M_ to coil _K_ where it is
entirely liquefied. If the liquid in _E_ rises beyond a certain level it
passes through pipe _e_ back to the still. Any vapors which may collect
in the upper part of _D_ pass into the small bent pipe opening into the
first coil of worm _C_. Water for rinsing the heater _D_ may be drawn
through cock _s_ from the tub _J_ and warm water for rinsing the still,
through pipe _d_ from the heater.
Another form of compound still is shown in Fig. 13. In this the still _S_
is divided into an upper and lower compartment by a concavo-convex
partition _d_, having at its crown an upwardly extending tube _t_ from
which projects side tubes _p_. A pipe _P_ opens above and extends from
tube _t_. _C_ is the mash heater and condenser. Connected to the head of
the still is a pipe _T_ through which the vapors pass to a condensing
coil _f_ formed on the wall of the heater _C_. At its bottom the coil _f_
extends out of the heater, through the water tub _W_ and out to receiver
as at _F_. In the heat of this heater is a valve _V_ whereby any vapors
which may arise from the heated mash are conducted by pipe _U_ to _T_.
The heater _C_ is filled through funnel _Y_ and the mash is admitted to
the still through pipe _b_ having cock _a_. The pipe _P_ extends to the
upper part of the water tub _W_ and then downward to the bottom, where it
again enters the still.
An opening in the partition _d_ is controlled by a valve _G_ which allows
liquid in the upper compartment of the still to flow into the lower.
Spent mash may be drawn off through _c_ and the height of the water in
tub _W_ be regulated by pipe _Z_.
[Illustration: FIG. 13.--Compound Still.]
The operation of this still is similar to Dorn's still. Mash is put into
_C_ and a quantity of it is let into the upper compartment of the still
and into the lower compartment by valve _G_. This valve is closed and the
fire started. The vapors pass upward through _t_. If they are quite
highly vaporized they pass onward up _P_, are condensed in their passage
through the cool water tub and return as liquid to the upper compartment
where they are further heated.
The liquid in the upper compartment is thus constantly enriched and the
vapor therefrom passes out through pipe _T_ into condensing coils _f_
where it is condensed into spirit and passes off by _F_.
The funnel tube _Y_ acts also as a means of warning the attendant as to
the condition of the mash. If it is too high in level and the pressure of
vapor in the heater _C_ too great, liquid will be forced out of _Y_; if
on the contrary, the mash sinks below the level of the pipe then vapor
will escape and the heater needs refilling.
[Illustration: FIG. 14.--Compound Direct Fire Still.]
Fig. 14 shows a simple form of compound direct fire still as manufactured
by the Geo. L. Squier Mfg. Co., of Buffalo, N. Y.
Cellier-Blumenthal carrying this principle further devised an apparatus
which has become the basis of all subsequent improvements; indeed, every
successive invention has differed from this arrangement merely in detail,
the general principles being in every case the same. The chief defect in
the simple stills was that they were intermittent that is required the
operations to be suspended when they were recharged, while that of
Cellier-Blumenthal is continuous; that is to say, the liquid for
distillation is introduced at one end of the arrangement, and the
alcoholic products are received continuously, and of a constant degree of
concentration, at the other. The saving of time and fuel resulting from
the use of his still is enormous. In the case of the simple stills, the
fuel consumed amounted to a weight nearly three times that of the spirit
yielded by it; whereas, the Cellier-Blumenthal apparatus reduces the
amount to one-quarter of the weight of alcohol produced. Fig. 15 shows
the whole arrangement, and Figs. 16 to 17 represent different parts of it
in detail.
[Illustration: FIG. 15.--Cellier-Blumenthal Still.]
In Fig. 15 _A_ is a boiler, placed over a brick furnace; _B_ is the
still, placed beside it, on a slightly higher level and heated by the
furnace flue which passes underneath it. A pipe _e_ conducts the steam
from the boiler to the bottom of the still. By another pipe _d_, which is
furnished with a stop cock and which reaches to the bottom of the still
_A_, the alcoholic liquors in the still may be run from it into the
boiler; by turning the valve the spent liquor may be run out at _a_. The
glass tubes _b_ and _f_ show the height of liquid in the two vessels. _K_
is the valve for filling the boiler and _c_ the safety valve.
[Illustration: FIG. 16.--Details of Rectifier Column.]
The still is surmounted by a column _C_, shown in section in Fig. 16.
This column contains an enriching arrangement whereby the liquid flowing
down into the still _B_ is brought into intimate contact with the steam
rising from the still. The liquid meets with obstacles in falling and
falls downward in a shower, which thus presents multiplied obstacles to
the ascent of the vapor. The liquid is thus heated almost to the boiling
point before it falls into the still _B_. The construction for effecting
this is shown at _C_, Fig. 16 and consists of an enclosed series of nine
sets of circular copper saucer-shaped capsules, placed one above the
other, and secured to three metallic rods passing through the series so
that they can be all removed as one piece. These capsules are of
different diameters, the larger ones which are, nearly the diameter of
the column, are placed with the rounded side downwards, and are pierced
with small holes; the smaller ones are turned bottom upwards, a stream of
the liquid to be distilled flows down the pipe _h_ from _E_, into the top
capsule of _C_ and then percolating through the small holes, falls into
the smaller capsule beneath, and from the rim of this upon the one next
below, and so throughout the whole of the series until it reaches the
bottom and falls into the still _B_. The vapors rise up into the column
from the still and meeting the stream of liquid convert it partially into
vapor which passes out at the top of _C_ considerably enriched, into the
column _D_.
Fig. 16 shows a sectional view of the column _D_, the "rectifying column"
as it is called. It contains six vessels, placed one above the other, in
an inverted position, so as to form seals. These are so disposed that the
vapors must pass through a thin layer of liquor in each vessel. Some of
the vapor is thus condensed and the condensed liquid flows back into
column _C_, the uncondensed vapor considerably enriched passing up the
pipe _J_, into the coil _S_ in the condenser _E_, Fig. 17, which is
filled with the "wash" to be distilled.
[Illustration: FIG. 17.--Details of Condenser and Mash Heater.]
Entering by the pipe _t_, Fig. 15, the undistilled liquid or "wash" is
distributed over a perforated plate _y y_, and falls in drops into the
condenser _E_, where it is heated by contact with the coil _S_ containing
the heated vapors. The condenser is divided into two compartments by a
diaphragm _X_ which is pierced with holes at its lower extremity;
through these holes the wash flows into the second compartment, and
passes out at the top, where it runs through the pipe _h_, into the top
of the column _C_.
The vapors are made to traverse the coil _S_, which is kept at an average
temperature of 122∞ F., in the right hand compartment, and somewhat
higher in the other. They pass first through _J_ into the hottest part of
the coil, and there give up much of the water with which they are mixed,
and the process of concentration continues as they pass through the coil.
Each spiral is connected at the bottom with a vertical pipe by which the
condensed liquors are run off; these are conducted into the retrograding
pipe _p p_. Those which are condensed in the hottest part of the coil,
and are consequently the weakest, are led by the pipe _L_ into the third
vessel in the column _D_, Fig. 16, while the stronger or more vaporized
portions pass through _L¥_ into the fifth vessel. Stop-cocks at _m_, _n_,
_o_ regulate the flow of the liquid into these vessels, and consequently
also the strength of the spirit obtained.
Lastly, as the highly concentrated vapors leave the coil _S_ at _R_, they
are condensed in the vessel _F_, which contains another coil. This is
kept cool by a stream of liquid flowing from the reservoir _H_ into the
smaller cistern _G_ from which a continuous and regular flow is kept up
through the tap _v_ into a funnel _N_ and thence into condenser _F_. It
ultimately flows into condenser _E_ through pipe _t_, there being no
other outlet. The finished products run out by pipe _x_ into suitable
receivers.
It will be seen that the condenser _E_ has two functions. First it
condenses the alcoholic vapors before transmitting them to the final
condenser _F_, rejecting and sending back those vapors which are not
highly enough vaporized. Second it heats the wash intended for distilling
by appropriating the heat of the vapors to be condensed. Thus two birds
are killed with one stone. It will be noticed that the same result is
accomplished in the columns _C_ and _D_. This is the principle of all
modern stills.
Another form of still which is very analogous to that last described is
Coffey's apparatus, shown in Fig. 18, and is the immediate prototype of
the stills used to-day in all but the simplest plants.
[Illustration: FIG. 18.--Coffey's Rectifying Still.]
It consists of two columns, _C_ the analyser, and _H_ the rectifier,
placed side by side and above a chamber containing a steam pipe _b_ from
a boiler _A_. This chamber is divided into two compartments by a
horizontal partition _a_ pierced with small holes and furnished with four
safety valves _e e e e_. The column _C_ is divided into twelve small
compartments, by means of horizontal partitions of copper, also pierced
with holes and each provided with two little valves _f_. The spirituous
vapors passing up this column are led by a pipe _i_ to the bottom of the
second column or _rectifier_. This column is also divided into
compartments in precisely the same way, except that there are fifteen
of them, the ten lowest being separated by the partitions, which are
pierced with holes. The remaining five partitions are not perforated, but
have a wide opening as at _w_, for the passage of the vapors, and form a
condenser for the finished spirit. Between each of these partitions
passes one bend of a long zig-zag pipe _m_, beginning at the top of the
column, winding downwards to the bottom, and finally passing upwards
again to the top of the other column, so as to discharge its contents
into the highest compartment. The apparatus works in the following way:
The pump _Q_ is set in motion, and the zig-zag pipe _m_ then fills with
the wash or fermented liquor until it runs over at _n_ into the highest
compartment of column _C_. The pump is then stopped, and steam is
introduced through _b_, passing up through the two bottom chambers and
the short pipe _F_ into the analyzing column, finally reaching the bottom
of the other column by means of the pipe _i_. Here it surrounds the coil
pipe _m_ containing the wash, so that the latter becomes rapidly heated.
When several bends of the pipe have become heated, the pump is again set
to work, and the hot wash is driven rapidly through the coil and into the
analyzer at _n_. Here it takes the course indicated by the arrows,
running down from chamber to chamber through the tubes _h_ until it
reaches the bottom; none of the liquor finds its way through the
perforations in the various partitions, owing to the pressure of the
ascending steam.
As the liquid cannot pass through the holes in the partitions it can only
pass downward through the drop-pipe tubes _h_. By this means the mash is
spread in a thin stratum over each partition to the depth of the seal _g_
and is fully exposed to the steam forcing its way up through the holes,
the alcohol it contains being thus volatilized at every step.
In its course downwards the wash is met by the steam passing up through
the perforations, and the whole of the spirit which it contains is thus
converted into vapor. As soon as the chamber _B_ is nearly full of the
spent wash, its contents are run off into the lower compartment by
opening a valve in the pipe _V_. By means of the cock _E_, they are
finally discharged from the apparatus. This process is continued until
all the wash has been pumped through.
The course taken by the steam will be readily understood by a glance at
the figure. When it has passed through each of the chambers of the
analyzer, the mixed vapors of water and spirit pass through the pipe _i_
into the rectifying column. Ascending again, they heat the coiled pipe
_m_, and are partially deprived of aqueous vapors by condensation. Being
thus gradually concentrated, by the time they reach the opening at _w_
they consist of nearly pure spirit, and are then condensed by the cool
liquid in the pipe, fall upon the partition and are carried away by the
pipe _y_ to a refrigerator _W_. Any uncondensed gases pass out by the
pipe _R_ to the same refrigerator, where they are deprived of any alcohol
they may contain. The weak liquor condensed in the different compartments
of the rectifier descends in the same manner as the wash descends in the
other column; as it always contains a little spirit, it is conveyed by
means of the pipe _S_ to the vessel _L_ in order to be pumped once more
through the apparatus.
=The condensed spirit= gathered over the plates _v_ passes out through
the pipe _y_ to the condensing worm _T_. If any vapors escape the
condensing plates they pass into _R_ and are condensed in the worm _T_
also. From worm _T_ the spirit flows into a suitable receiver _Z_.
Before the process of distillation commences, it is usual, especially
when the common Scotch stills are employed, to add about one lb. of soap
to the contents of the still for every 100 gallons of wash. This is done
in order to prevent the liquid from boiling over, which object is
effected in the following way: The fermented wash always contains small
quantities of acetic acid; this acts upon the soap, liberating an oily
compound which floats upon the surface. The bubbles of gas as they rise
from the body of the liquid are broken by this layer of oil, and hence
the violence of the ebullition is considerably checked. Butter is
sometimes employed for the same purpose.
Figs. 19 and 20 show a diagrammatic section and a plan of a still used
for thick mashes which are liable to burn. This comprises a circular
chamber _B_ supported over suitable heating means, having on its bottom a
series of concentric partitions _b_ which divide the bottom of the
chamber into shallow channels for the mash. Running diametrically through
the chamber is a partition.
[Illustration: FIG. 19.--Rotary Current Still.]
The mash passes from a tank as _A_ by a passage _a_ to an opening on one
side of the central portion and into the outside channel _b_. The current
of liquid passes along the outer channel until it is deflected by the
central partition into the next interior channel _b_ and so on until it
arrives at the center when it passes through the central partition into
the other half of the chamber. Here it passes around back and forth and
gradually outward to the outermost channel from which it passes off
through an adjustable gate in outlet _c_. By adjusting this gate, and a
gate or cock in inlet passage _a_, the passage and consequent depth of
the liquid in the channels may be regulated. The vapor rising from the
mash is carried over to a condenser through pipe _D_. In order to keep
the mash from burning a chain _g_ is rotarily reciprocated along the
channels by means of the bar _G_, the gear _E_ and the crank shaft _e_.
Various modifications of this construction have been devised. The
advantage of the still lies in submitting the mash in a thin current to
the action of the heat, and the consequent rapid vaporization.
[Illustration: FIG. 20.--Rotary Current Still.]
Every distillation consists of two operations: The conversion of liquid
into vapor, and the reconversion of the vapor into liquid. Hence perfect
equilibrium should be established between the vaporizing heat and the
condensing cold. The quantity of vapor must not be greater or less than
can be condensed. If fire is too violent the vapors will pass out of the
worm uncondensed. If the fire is too low the pressure of the vapor is
not great enough to prevent the entrance of air, which obstructs
distillation. As a means of indicating the proper regulation of the fire,
the simple little device shown in Fig. 21 may be used.
This consists of a tube of copper or glass having a ball _B_ eight inches
in diameter. The upper end _E_ of the tube is attached to the condensing
worm. The lower end of the tube is bent in U-shape; the length of the two
bends from _b_ to outlet is four feet. The ball has a capacity slightly
greater than the two legs of the bend.
[Illustration: FIG. 21.--Indicator for Regulating the Distilling Fire.]
Normally the liquid in the two legs will stand at a level. If, however,
the fire is too brisk the vapor will enter the tube and drive out the
liquor at _d_, and thus the level in the leg _C_ will be less than in the
leg _D_. If, however, the fire is low, the pressure of vapor in the worm
will decrease and the pressure of the outside air will force down the
liquid in leg _D_ and up leg _C_ into the ball.
A more perfected device but operating on the same principle is shown in
Fig. 26.
It is obviously impossible to present in the small compass of this book a
description of all the varieties of stills used, but these which have
been described illustrate the principles on which all stills are
constructed and were chosen for their simplicity of construction and
clearness of their operation. The principle of their operation is exactly
the same as the more modern forms now to be described.
CHAPTER IV.
MODERN DISTILLING APPARATUS.
In the previous chapter we have given a description of small, simple
stills, such as were used until late years, and which are yet used in
many localities where distilling is carried on on a small scale. We will
now describe the principle features of more complicated and elaborate
apparatus.
All modern distilling apparatus for the production of a high grade of
alcohol is based upon the principle set forth in the description of the
Coffey still; that is, upon using a distilling column and a concentrating
column, wherein the "wash" or mash fermented as described, passes over a
series of plates or other obstructions in contact with an ascending
column of heated vapor. This heated vapor extracts the alcohol from the
wash, or from the low wines of the concentrator, and is continually
strengthened during its journey until it passes off to a condenser as a
vapor very rich in alcohol. The converse of this is true with the wash,
which in its downward course is gradually deprived of its alcohol until
it finally passes off at the bottom of the column.
[Illustration: FIG. 22.--Diagramatic View of Column Still and Accessory
Apparatus. (_To face page 64_)]
Fig. 22 is illustrative of the general form and arrangement of such a
column and its adjuncts; the details, however, will vary with each make
of still. In this the "column" consists of a casing really continuous but
divided into two portions--the distilling portion _A_ and the rectifying
portion _B_. The operation is alike, however, in principle in both
portions.
[Illustration: Cross-Section of Fig. 23.]
[Illustration: FIG. 23.--Distilling Plate.]
The wash by means of a suitable pump is forced into an overhead tank or
concentrator _G_ where it is warmed by the hot vapors as will be later
described. It passes around the interior of the concentrator in a coil
_c_ and then passes off by a pipe _a_ to the uppermost plate of the
distilling portion _A_ of the column.
The plates, as before explained on page 55, are each formed with a
dropping tube _O_ (see Fig. 23), which extends above the plate to an
extent slightly less than the desired thickness of the layer of liquid on
each plate, and with perforations each having an upwardly projecting rim,
and each covered with a cap _A_. This rim and cap form a trap. The
ascending vapors pass up through the perforations, down between the rim
and the edge of the cap and thus out through the layer of wash contained
on the cap. The wash remains constantly level with the top of the tube
_O_, the excess running off through the tube _O_ to the compartment or
plate beneath.
To return to Fig. 22, the wash by the pipe _a_ enters the distilling
portion of the column at the uppermost plate thereof and, as described
above, drops down from plate to plate. A steam pipe _S_ enters the bottom
compartment of the distilling portion of the column and the steam as it
rises through the little traps, bubbles out through the layer of wash and
in each compartment enriches itself with alcohol. Thus the rising column
of vapor is constantly becoming richer and the downward current of wash
constantly weaker until at last it passes away as spent wash at the very
bottom of the column by the pipe _D_.
The hot vapors, as before described, pass upward and enter the rectifying
portion of the column _B_. This consists of a series of compartments
having perforated bottoms and dropping tubes. The vapor passes upward
through these perforations of the plates,--the condensed portion of it
dropping back again on to the lower plates or on to the distilling plates
to be again vaporized and concentrated and the more highly vaporized
portion passing out at the top of the column through the pipe _E_ to the
concentrator _G_.
The concentrator consists of a tank containing water within which is
supported a vessel _F_ having double walls. The interior of this vessel
is likewise filled with water. Between the double walls and surrounding
the coiled pipe _c_ passes the vapors from pipe _E_.
At the bottom of the vessel _F_ is a compartment _f_ connected by a pipe
_F¥_ with the upper compartment of the rectifying column. The less highly
heated vapors will be condensed by the passage through the double walls
of the vessel and the condensation will collect in the compartment _f_,
and from there pass off by pipe _F¥_ back to the rectifying column, to be
again vaporized and strengthened by the descent from plate to plate of
_B_.
The rich and highly vaporized vapors which have passed the test of this
preliminary concentration, pass out of the compartment _f_ by a pipe _M_.
Here again the water surrounding the pipe tends to condense all but the
most highly charged vapor and send it back to compartment _f_ but the
vapor which succeeds in passing over through pipe _G_ is carried downward
to a condenser _H_ where it is finally condensed and drawn off as at _g_.
It is necessary that the rate of mash feed be regulated so that neither
too much mash shall be pumped into the mash heater _G_, or too little,
and the pipe leading from the pump to the heater is therefore provided
with a tap and an indicating dial.
In these modern stills the following are particularly important points to
be especially brought to the consideration of the distiller.
It cannot be too strongly impressed that effectiveness of the distilling
column depends on the plates dividing it,--that is, upon the
horizontality of the plates and the form of the traps or perforations. If
the plates are not horizontal the wash is not maintained at a uniform
level across the entire extent of the plate and hence some of the
ascending vapor will pass out without contacting with the wash through
uncovered traps, while others of the traps will be so deeply submerged in
wash that the vapor cannot bubble through.
Again the caps should be so made as to divide the vapor into fine streams
and bring it into contact with each part of the wash. Plates simply
perforated and uncapped give excellent results for they molecularize the
vapor ascending through the liquid contained on the plates, but they
require a constant pressure of vapor, and any variations of pressure
tends to discharge them. In addition these perforations gradually enlarge
by the action of acids in the wash or clog up, and the apparatus soon
works badly.
Good forms of capped traps are those shown in Figs. 24, 25 devised by
Barbet. These are provided with an interior upwardly projecting rim.
Extending over the rim and down around it is a copper cap having its
margin slitted.
The wash carried on the plate circulates about the caps and the alcoholic
vapors bubble out through the slits and up through the wash, the vapor
thus being finely divided and coming into intimate contact with each
portion of the wash and thus more thoroughly depriving it of its alcohol.
[Illustration: FIG. 24.--Barbet Trap.]
[Illustration: FIG. 25.--Barbet Trap.]
Besides this there is another advantage resident in these caps, namely,
that distillation may be stopped for several hours and then re-started
without trouble for the reason that the wash has been retained on the
plates, whereas were the plates simply perforated the wash would ooze
through and the plates have to be recharged. This form of plate may be
easily repaired and does not necessitate the removal or replacement of
the plate itself. The caps alone need be removed.
For thick washes, which tends to obstruct the slits of the cap, Barbet
has devised the cap shown at the right in Fig. 25. This cap extends down
to the plate itself, and has very narrow slits in its periphery. With
such a cap as shown in Fig. 24, the bran, sediments, etc., would tend to
settle upon the top of the cap, enter beneath it and through the slits.
The cone-shape of the top of this cap prevents the deposit of dregs
thereon and the very narrow slits oppose the entrance of bran or
sediment.
While, for the sake of clearness, an old form of concentrator, _G_, has
been shown, the concentrator, preheater for the wash, and condensers,
to-day, are usually composed of bundles of tubes through which the vapors
pass surrounded by water or the cool wash. These should be of bronze or
copper and made without solder. The tubes should be capable of being
taken out for cleaning or repairing.
In many distilling apparatuses the distilling column and the rectifying
column are in two parts, one beside the other. This overcomes the
objection of having a very high column and also prevents the low wines,
_i.e._, the weak alcoholic liquor after its first concentration, from
passing into the wash as it would do with the continuous column.
[Illustration: FIG. 26.--Steam Regulator.]
In order that the amount of steam entering the column may be regulated,
the column is usually provided with a steam regulator (Fig. 26); whose
principle of operation may be easily under stood by referring to Fig. 22.
It comprises an upper and a lower chamber _Z Z¥_ connected by a central
tube _K_ which projects down nearly to the bottom of the lower chamber. A
pipe _W_ communicates with the steam chamber _R_ of the column and enters
the chamber _Z_ above the level of the water contained therein. In the
upper chamber _Z¥_, is a float _X_, connected to the differential lever
_T_ of a steam valve _T¥_ which controls the inlet of steam passing
through pipe _S_ to the steam chest _R_. The principle of operation is
very simple. When the pressure in the steam chest _R_ becomes too great,
steam in the pipe _W_ and chamber _Z_ forces the water therein up in tube
_K_, thus lifting the float _X_ and closing the steam entrance valve
_T¥_. When the pressure of steam is low, the level of the liquid in _Z_
rises and liquid in _Z¥_ runs into _Z_, the float _X_ falls opening valve
_T¥_ and allowing a greater flow of steam.
As it is often desirable to change the pressure of steam in the column at
various points in the operation, the best regulators are usually provided
with means to that end.
[Illustration: FIG. 27.--Gauge Glass for Regulatur.]
In order to measure the output of the still, there is attached thereto a
gauge glass (_J_ in Fig. 22), a diagram of which is shown in Fig. 27.
This consists of a jar _A_ connected at its lower end at _b_ by an
annular passage _B_ to a chamber _E_ from which proceed the taps _F_.
Centrally through the passage _B_ passes a tube _c_ connected at its
lower end to the pipe _C_ leading from the condenser. The tube _C c_
projects upward into the jar _A_ and is open at its upper end.
Now the opening _b_ is of a certain size and it is obvious that it will
carry off a certain amount of liquid when running full or the amount
allowed to flow out by the exit tap _F_. If now, more than that quantity
of alcohol is produced, the alcohol will rise in the jar _A_ until the
rate of inflow and outflow is equal. If, however, the still is producing
less than that quantity then the level of liquid in _A_ will gradually
drop. Hence, by observing the level of the liquid in _A_ and its
constancy or variation in level, it is possible to tell precisely how
much alcohol is running per hour and if the rate is steady. The jar _A_
is provided with a cap _G_ whereby an alcoholometer may be inserted
into tube _c_ for the purpose of testing the strength of the liquor. The
taps _F_ are for the purpose of collecting the first runnings, the pure
alcohol and the last runnings or "feints."
These principles are also embodied in the apparatus designed by the
Vulcan Copper Works Co., of Cincinnati, and illustrated in Fig. 28. The
apparatus comprises the still, a wash heater and a condenser. The still
is composed of a series of chambers from 12 to 24, the internal
construction of which is shown in Fig. 29. Each chamber consists of a
peculiarly perforated plate _A_, a drop pipe _B_, a seal _C_, into which
the drop pipe from the plate above projects, and a central standard _D_.
Returning now to Fig. 28, at the bottom of the column is a manifold _E_,
with pipes _F_ and _G_ whereby either exhaust or live steam may be
admitted. _H_ designates the discharge or slop valve, controlled by a
float _I_ whereby a constant level of slop or spent wash is kept in the
bottom chamber.
[Illustration: FIG. 28.--Continuous Distilling Apparatus, with External
Tubular Condenser. (_To face page 72_)]
To the right of the column is seen the slop tester _J_ and hydrometer
_L_, whereby the spent wash may be tested to see if the spirit is being
properly extracted. The steam pressure is indicated by means of a float
_N_ contained within a vessel _M_, a tally weight moving against a scale
_K_, showing the pressure of steam entering through pipe _O_ and acting
against water contained in vessel _M_. Each chamber is provided with a
manhole plate _P_, and a try-cock _Q_, whereby the operation of each
chamber may be tested. _R_ is a gage glass to show the level of the slop
in the bottom chamber.
At the top of the column are three rectifying chambers fitted with
boiling pipes and traps _T_, which distribute the ascending vapor and
boil out the low wines returned from the wash-heater or fore-warmer.
[Illustration: FIG. 29.--Detail of Chamber, Continuous Still.]
The heater consists of a shell enclosing a series of tubes extending into
an upper and lower chamber. The wash or "beer," is pumped into the lower
chamber of the heater, and passes upward through the tubes to the upper
chamber from which is it carried by a pipe to the plate _A_ next below
the rectifying plates.
[Illustration: FIG. 30.--Detail of Perforated Plate _A_.]
The vapor from the column passes into the middle compartment of the
heater and surrounds the beer tubes. The vapors give their heat to the
beer and are thus cooled, the low wines being condensed and flowing back
onto the uppermost rectifying plate, while the highly vaporized portions
pass out to the condenser. This is of the same general construction as
the heater, the vapor being cooled and condensed to liquid by the tubes
through which a constant current of cool water is passed. This enters at
_U_ and passes out at _V_. These tubular condensers are particularly good
as they may be easily cleaned. From the condenser the spirit passes to a
discharge box _W_. A portion of the flow passes into a test tube _X_,
provided with a hydrometer. A trap _Y_ and an air pipe _Z_ provide means
for the escape of gas.
As before stated, the form of perforations in the plates of a column
through which the vapor pass upward through the beer or wash is
particularly important. The steam must be thoroughly diffused through the
beer, or else particles of mash are carried up, accumulate around the
perforations, baking there and clogging them up. The clogging and
eventual stoppage of the perforations prevent the agitation of the mash
carried on the plate, and a layer of mash accumulates and bakes on the
head, or plate, above. Thus the operating capacity of the still is
reduced and a larger quantity and greater pressure of steam is necessary
with consequent waste of fuel.
[Illustration: FIG. 31.--Detail of Perforated Plate _A_.]
It is necessary then that the form of perforation or trap through which
the vapor ascends should be such that agitation of the beer shall be
enforced in its movement across the plate, and that the steam shall be
thoroughly diffused through the beer. In the Vulcan still above referred
to, these results are accomplished by forming each perforation with a
tongue, as shown in the fragmentary view of a plate, Figs. 30 and 31, the
tongues of all the holes being directed towards the periphery of the
plate. It is claimed that by this construction the steam is diverted
forward and injected into the beer, throwing the beer into vigorous
motion, completely diffusing the steam and accelerating the motion of the
beer from the seal _C_ to the drop pipe _B_.
[Illustration: FIG. 32.--Continuous Distilling Apparatus with Goose
Separator. (_To face page 76_)]
Fig. 32 illustrates another form of distilling apparatus manufactured by
the same company, which is practically the same as the apparatus
previously described except that it is provided with a "goose-necked"
separator, interposed between the wash-heater and the enclosure. This
consists of a series of convoluted tubes contained in a tank of cold
water. The vapor from the heater passes into these convolutions. The
heavier vapors are condensed therein and returned to the heater from
which they descend into the column while the more volatilized vapors pass
over into the final condenser. The _U_-bends at the bottoms of each
convolution act like so many low wine chambers in the still shown in Fig.
9 the highly heated vapor continually bubbling through the condensed
vapor in the _U_ bend and there becoming greatly enriched and
concentrated.
This apparatus, it is claimed, is applicable to the distillation of
grain, molasses or cane juice and will yield 170 or 180 per cent., or the
equivalent to 85-90 G. L. or 34-36 Cartier.
[Illustration: FIG. 33.--Section of Gillaume's Inclined Column Still.]
A distinctly modern type of still, though akin to the still shown in
Figs. 19 and 20, is the inclined column of Gillaume, shown in section in
Fig. 33 and in full view in Fig. 34. Gillaume in devising this form of
apparatus had particularly in mind the distillation of thick washes, and
the necessity of compelling a circulation of the wash.
[Illustration: FIG. 34.--Gillaume's Inclined Column Still.]
The bottom of the inclined column _A_ is divided by lateral extending,
upwardly projecting plates or partitions _a_ forming a continuous
channel through which the wash passes from side to side and from top to
bottom and then out through a regulator. The upper plate of the column
has downwardly projecting partitions _b_ which with the partitions _a_
form a series of traps. The steam enters at the bottom of the column into
a reservoir, and in order to pass upward is forced beneath each partition
_b_ and through the washer contained in the channels of the bottom. When
it reaches the upper end of the column it has passed through a continuous
series of wash-filled compartments containing a constantly moving current
of wash.
The vapors from the top of the column pass off to the wash heater or to a
concentrator.
In Fig. 34 is shown a form of Gillaume still designed to distill all
sorts of liquids whether thin or thick. The wash is supplied from an
overhead tank to a regulating tank _K_ from which a pipe _k_ leads to a
regulating tap _m_. The wash re-ascends into the wash heater _B_ and when
heated descends by pipe _F_ into the uppermost compartments of the column
_A_. The vapor passes to the condenser _B_, by a pipe _H_, and the spent
wash is discharged by a siphon _C_. In addition to the parts above
referred to, _a_ designates entrance of wash into heater, _b_ exhaust
test tube, _d_ steam entrance tap _G_ alcohol test glass, _G¥_ exhaust
test glass, _o_ valve for regulating strength of spirit, _O_ steam
regulator, _p_ water entrance tap, _r_ exit tap, and _D_ the spent wash
extractor.
The Gillaume apparatus is particularly valuable for the production of
industrial or agricultural alcohol. It is claimed that it is easily
understood and operated even by unskilled labor, while it produces a
large proportion of alcohol of a high strength.
A view of a complete apparatus on a large scale is shown in the Fig. 40
in the chapter on rectification.
CHAPTER V.
RECTIFICATION.
The product of the distillation of alcoholic liquors, which is termed
_low wine_, does not usually contain alcohol in sufficient quantity to
admit of its being employed for direct consumption. Besides this it
always contains substances which have the property of distilling over
with the spirit, although their boiling points, when in the pure state,
are much higher than that of alcohol. These are all classed under the
generic title of _fusel-oil_; owing to their very disagreeable taste and
smell, their presence in spirit is extremely objectionable. In order to
remove them, the rough products of distillation are submitted to a
further process of concentration and purification. Besides fusel-oil,
they contain other substances, such as aldehyde, various ethers, etc.,
the boiling points of which are lower than that of alcohol; these must
also be removed, as they impart to the spirit a fiery taste. The whole
process is termed _rectification_, and is carried on in a distillatory
apparatus.
As before stated, the wash as discharged into the still consists of
alcohol mixed with water and a variety of impurities from which the
alcohol must be separated. In order that the process may be better
understood we will assume that a mixture of pure alcohol and water is to
be operated on in place of the wash as above referred to. Distillation in
this case is intended to deprive the water of its alcohol, the operation
theoretically leaving water in one chamber and alcohol in another. This
is accomplished by reason of the differences in the boiling points of
water and alcohol. The alcohol vaporizes at a lower degree (173∞ F.) than
water (212∞ F.) Thus the liquid at the end of the operation has been
divided into two parts or _fractions_.
This, however, is not a clean division for the reason that while in the
beginning the vapors contain a large quantity of the more volatile
alcohol, at the end they will contain a large portion of the less
volatile water. The whole of the alcohol will be separated in this
manner, but it will still be mixed with some water and in order to again
divide the alcohol from the water the first distillate would have to be
redistilled until at last the water is reduced to a minimum or entirely
eliminated, if possible.
But as it requires less heat to vaporize alcohol than water, so it also
requires more cold to condense alcoholic-vapor than water-vapor. If then
we pass the mixed vapors into a condensing chamber cooled to a certain
temperature low enough to condense water-vapor but not the alcohol-vapor,
then the water-vapor will fall down as water while the alcohol-vapor
being uncondensed passes on to another chamber where its temperature
falls to a point where it in turn condenses into liquid.
In intermittent distillation, as by the simple still, the vapors of mixed
alcohol and water at first contain a great deal of alcohol and a little
water, then more water and less alcohol, and then a great deal of water
and hardly any alcohol. It may be asked: "Why not take only the runnings
rich in alcohol and leave the others?" The answer to this is that if this
be done then _all_ the alcohol is not extracted from the wash and there
is just that much loss. The solution of the problem is to get all the
alcohol out mixed with the water that is inevitably with it and then
redistill this result thus getting out (sifting away) some of the water,
and again distill this result, and so on until only pure alcohol is left.
This, however, is a very troublesome business and has been abandoned as a
means of removing impurities such as water, the ethers, and fusel oil
except by makers of whiskey, brandy and other beverage spirits, in favor
of continuous distillation and continuous rectification.
It will be seen from what has gone before that there are two means of
separating alcohol and water; one by an initial difference in heating and
by a further difference in cooling or condensing.
It is on this foundation that the whole art of fractional distillation or
rectification rests. While we have for illustration been considering a
mixture of pure alcohol and water, the wash or liquid formed by the
fermentation of grain, etc., contains a variety of ingredients of
different boiling points, some more volatile than alcohol, some less. The
fermented wash consists first of non-volatile or only slightly volatile
matters, such as salts, proteins, glycerin, lactic acid, yeast, etc., and
second, volatile bodies such as alcohol, water, various ethers, etc.,
fusel oils and acetic acid.
When wash is distilled in the ordinary simple or pot still, the first
part to come over consists of the very volatile matters,--more volatile
than alcohol even,--that is, the ethers mixed with some alcohol. This is
known as the fore-shot or first runnings, and is collected separately.
When the spirit coming over possesses no objectionable odor, the second
stage has begun. This running would be of the alcohol proper, getting
weaker and weaker, however, as the running continues and this would be
caught separately as long as it is of sufficient strength. At last would
come the weak spirit containing much fusel oil. It is to be understood,
however, that there is no defined line between these divisions. They
graduate one into the other. The first and last runnings in the old
practice were mixed together and distilled with the next charge. When a
strong spirit was required, rectification would be repeated several
times. It is customary, however, with the improved modern apparatus, to
produce at the outset spirit containing but little fusel oil and at least
80 per cent of alcohol. This is then purified and concentrated in the
above manner and afterwards reduced with water to the required strength.
Another cause of the offensive flavor of the products of distillation is
the presence of various acids, which exist in all fermented liquors; they
are chiefly tartaric, malic, acetic, and lactic acids. The excessive
action of heat upon liquors which have been distilled by an open fire has
also a particularly objectionable influence upon the flavor of the
products.
The first operation in the process of rectification is to neutralize the
above-mentioned acids; this is effected by means of milk of lime, which
is added to the liquor in quantity depending upon its acidity; the point
at which the neutralization is complete is determined by the use of
litmus paper. In the subsequent process of distillation, the
determination of the exact moments at which to begin and to cease
collecting the pure spirit is very difficult to indicate. It must be
regulated by the nature of the spirits; some may be pure 20 or 30 minutes
after they have attained the desired strength; and some only run pure an
hour, or even more, after this point. The product should be tasted
frequently, after being diluted with water, or a few drops may be poured
into the palm of the hand, and after striking the hands together, it will
be known by the odor whether the spirit be of good quality or not; these
two means may be applied simultaneously.
[Illustration: FIG. 35.--Rectifying Still.]
The process of rectification may be carried on in the apparatus shown in
Figs. 35 and 36. _A_ is a still which contains the spirit to be
rectified; it should be four-fifths full. The condenser _E_ and the
cooler _G_ are filled with water. After closing the cocks _L_ and _I_,
the contents of the still are heated by steam, which is introduced at
first slowly. The vapors of spirit given off pass, by tubes _b_, above
each plate _a_, of the series in column _B_, and escape through _C_ and
_D_ into the condenser _E_, where they are condensed on reaching the
lentils _d d¥_, and return in a liquid state through pipe _f_ and
connections _g g¥_ to the upper plates of the column _B_. In these return
pipes the liquid is volatilized, and constantly recharged with alcohol to
be again condensed, until the water in the condenser is hot enough to
permit the lighter alcoholic vapors to pass into the coil _c c c_,
without being reduced to the liquid state. When this is the case, the
vapors pass through _F_ into the cooler _G_, where they undergo complete
condensation. Great care must be taken that the heat is not so great as
to permit any of the vapors to pass over uncondensed or to flow away in a
hot state; and also to keep up a constant supply of water in the cooler
without producing too low a temperature; the alcoholic products should
run out just cold. The highly volatile constituents of the spirit come
over first, that which follows becoming gradually purer until it consists
of well-flavored alcohol; after this comes a product containing the
essential oils. The more impure products are kept apart from the rest
and re-distilled with the next charge. Some hours generally elapse before
alcohol begins to flow from the cooler. The purest alcohol is obtained
while its strength is kept between 92∞ and 96∞ Baume, and the operation
is complete when the liquid flowing through the vessel marks not more
than 3∞ or 4∞ Baume; it is better, however, to stop the still when the
backing or "faints" indicate 10∞, because the product after this point
contains much fusel-oil, and is not worth collecting.
[Illustration: FIG. 36.--Section of Rectifying Still.]
In order to cleanse the apparatus--which should be performed after each
working--the still _A_ is emptied of water by opening the cock _Q_. The
contents of the condenser are then emptied in like manner by opening the
cock _J_, through which they flow upon the plates in the column _B_, and
wash out essential oils which remain in them. These two cocks are then
closed, and the door _U_ in the still head is removed. The water in the
cooler _G_ is then run by means of pipe into the still _A_, so as
partially to cover the steam-coil in the latter. After again securing the
door _U_, a strong heat is applied, and the water in the still is well
boiled, the steam evolved thoroughly cleansing all the different parts of
the apparatus; this is continued for 15 or 20 minutes, when the heat is
withdrawn and the still left to cool gradually.
In the intermittent rectifying still above described the impure products
are distilled with the next charge. In the apparatus as perfected and
used in large distilleries or rectification plants, the division of the
several products composing the phlegm or raw spirit is made at one time
and continuously on the principle now to be described.
It was stated in the beginning of this chapter that the various
impurities in alcohol, the ethers, the water and the fusel oils, have
each their own vaporizing point and each their own condensing point. As
this is so, they may be separated from each other and from the alcohol on
the same principle as we have seen that water is separated from the
mixture of pure alcohol and water; that is, by fractionation, as it is
termed, or by "sifting out" one body from another.
[Illustration: FIG. 37.--Fractional Distilling Apparatus.]
Thus in fractional distillation, each condenser or retort in the
apparatus shown in Fig. 37, above acts as a sieve or trap, letting pass
the most volatile substances but retaining those of a less degree of
volatility. By passing the mixed vapor together through a good condensing
medium the temperature of which is lower than the boiling point of the
less volatile, but not so low as the boiling point of the more volatile
the vapors of the less volatile liquid will be condensed, while the more
volatile will retain their gaseous form. Thus by having a number of
condensing mediums each one slightly lower in temperature than the other,
the various vapors with their various points of volatilization will be
successively condensed, allowing the passage of the more volatile vapors
over to the condenser beyond.
If we had mixed gravel and sand and desired to separate the gravel into
assorted sizes and get the sand by itself, we would pass the mass through
a series of sieves of gradually smaller mesh. The first sieve of course
would catch all the largest pebbles, the next in size would let all the
second sized gravel through, and so on until the final sieve would have
separated the coarse sand from the fine. In this figure of illustration,
the coarse pebbles may be taken to represent the water and the fusel oils
which are mixed and partly tend to rise with the alcohol, and the alcohol
may be represented as the gravel larger than the sand, and the fine sand
as the etheric vapors. If this gravel were forced upwardly through a
series of sieves gradually growing finer, it would be analogous
figuratively to the upward passage of the vapors through a distilling
column composed of plates or chambers; the water and fusel oils would be
retained in the lower portion of the column and continually sent back
there; the alcohol would pass into the upper chambers of the column and
the ethers or fore-shots would pass out from the very fine sieve at the
top of the column.
The vertical chambers above each plate of the rectifying column are
to-day used as the separate eliminating chambers referred to above. It
has been found in practice that as before stated, each plate of a column
contained upon it liquid of a certain temperature and above it vapors of
a certain degree of vaporization. That is, in a continuous column fed
regularly by condensation from above and supplied with a constant flow of
phlegm, each plate carries upon it a liquid of constant composition
relative to the boiling point of the fluid on that plate. As many
extractions may thus be made from the various plates as there are
different liquids to be isolated. Thus by tapping different portions of
the column, vapors of different degrees of vaporization are found and may
be carried off and the phlegm be thus fractionated. In the case of one
column the first runnings or fore-shot would be found in the upper
portion of the column to which they would have risen by reason of their
degree of volatility. The last runnings or oils, aldehydes, etc., would
be found in the lower portion of the column still mixed with the spirit,
while upon the plates of the middle portion of the column would be found
the vapor of the alcohol freed from the fusel oils and from the,ethers.
It is understood, of course, throughout this description that the liquid
being treated is not wash but phlegm; that is, the raw spirit containing
the fusel oils, ethers, water and alcohol.
Fig. 38 represents a simple rectifying apparatus designed for small or
medium sized plants, and manufactured by the Vulcan Copper Works Co., of
Cincinnati. The still is upright, with a chambered column above it, of
the usual type. The chambers are fitted with a vapor boiling pipe and cap
and a drop pipe, and each is provided with cocks whereby it may be
drained for cleansing. Above the column is a separator, comprising a
casing containing a series of tubes. The vapor from the column circulates
around the tubes through which passes a current of cool water. The
condenser is of the same construction as the separator and is provided
with a gage glass and a draw-off cock. The operation is the same as in
other simple rectifiers; part of the vapor from the column is condensed
in the separator and passes back on to the upper plates, while the more
highly vaporized portions pass over into the condenser.
[Illustration: FIG. 38.--Rectifying Apparatus with External Tubular
Condenser. (_To face page 94_)]
The diameter of the still is large relatively to its depth so as to yield
an economical and at the same time highly effective distribution of heat
through the charge. This also affords an extended boiling area from which
the vapor rises evenly and regularly, thus ensuring conditions peculiarly
conducive to produce the best fractionating. The floor space required for
this still and others of the same character built by this company is very
compact and excessive weight on the top floor of the building is
dispensed with.
We have shown in Figs. 39 and 40 two forms of rectifying apparatus, one a
twin column Barbet rectifier and the other a rectifier of the Gillaume
type combined with inclined column still.
[Illustration: FIG. 39.--Twin Column Barbet Rectifier.]
In the twin column apparatus, Fig. 39, the first column or clarifier _A_
receives the raw phlegm and accomplishes the elimination of ethers. The
clarified phlegm passes then to the second column where the alcohol
is separated from the last runnings or fusel oil. In other words, the
phlegm or impure raw alcohol is only raised to such a temperature in the
first column as to drive off the very volatile constituents such as the
ethers. These therefore pass off at the top of the first column into the
condenser _C_, the retrogradation or condensed alcohol being returned to
_A_, while the boiling phlegm taken from the middle of the column and
still containing the aldehydes, oils, etc., is conducted by a pipe _E_ to
the second column _B_ wherein the last runnings or amylic oils, etc., are
separated from the purified spirits.
The vapors in this column are carried to the condensers _D_ and _F_ and
from there to a refrigerator _G_. The fusel oils are extracted from the
plates slightly below the center of the column and are carried to an oil
concentrating apparatus _H_.
In the most complete forms of apparatus used to-day, there is a variation
of this construction. The first runnings, middle runnings and the last
runnings are each led off from the main column to separate coolers,
condensers, etc., and the purified result from each of these columns is
in turn led to a trunk rectifier common to all where the product is
redistilled and entirely freed from impurities. This gives a very high
grade of alcohol by a process practically continuous. At the same time
the impurities are not returned to the first or main column to
contaminate the vapors therein and add to the amount of fusel oils
contained on the lower plates. In construction of this character there
is a very large saving in the cost of the fuel and the result is much
better in every way.
[Illustration: FIG. 40.--Gillaume's Rectifier and Inclined Still.]
FIG. 40.--GUILLAUME'S DIRECT DISTILLATION-RECTIFICATION APPARATUS FOR
"AGRICULTURAL" DISTILLATIONS.
_A_ Distilling Column.
_a_ Tank for Wash to be Distilled.
_b_ Cold Water Tank.
_C_ Rectification Column.
_D_ Final Purification Column.
_I_ Wash Heater.
_K_ Condenser.
_K¥_ Refrigerator of Ethers.
_O_ Refrigerator for high-grade Alcohol and the First Runnings.
_Q_ Refrigerator for the Products of the Last Runnings.
_R_ Spent Wash Extractor.
_r_ Siphon Carrying off Spent Wash.
_S_ Steam Regulator.
_s_ Tap and Pipe for Carrying Wash to Distilling Column.
_U_ Water Regulator.
_u_ Taps for the Extraction of Intermediate Impurities.
_V_ Receiver Accumulator.
_v_ Tap for the Extraction of the Last Runnings.
_X_ Test Glass for the High-Grade Alcohol.
_Y_ Test Glass for First Runnings.
_Y¥_ Test Glass for Last Runnings.
_Z_ Test Glass for Determining Degree of Exhaustion of Spent Wash.
In this apparatus the still proper is of the form heretofore described on
page 78. The liquid to be distilled enters at the top of the inclined
column _A_ and descends to the base thereof. The alcoholic vapor rises
through the column and passes off from the head thereof into the
rectifying column. At the head of the column _A_ it has a strength of
about 40∞ to 50∞ F. The column _C_ is supported upon an accumulating
reservoir _V_ which acts to regulate the flow of the phlegm through the
rectifying column and prevents too great an exhaustion of the plates of
the column. It acts as a reservoir to contain any excess of phlegm or to
supply an additional amount of phlegm to the plates when they have become
nearly exhausted.
The oils or products of the last running accumulate at the base of the
column, and are carried off to their special refrigerator _Q_. The
alcoholic vapors concentrate while rising in the column and quickly
attain a strength of 92∞ or 94∞ F. At a height within the column
corresponding to the plates whereon alcohol of that strength is to be
found, there are provided three taps _u_ whereby the middle runnings or
medium grade of alcohol may be drawn off, which have a maximum
concentration of 92∞ and 94∞ F. Above these middle plates the alcohol
vapors are completely separated from the products of the "tail" that is
the aldehydes, amylic oils, etc., and at the upper portion of the column
there is found the condenser _K_ which separates the products of the
head; that is the first runnings from the alcohol which has passed over
with such products to the condenser. The alcohol so separated is
completely rectified in the column of final purification _D_ and the
finished alcohol is cooled in the refrigerator _O_ below the column of
final condensation. In this apparatus the gauge glasses which regulate
the exit of the various alcohols and mixtures are controlled by taps
having verniers or scales whereby they may be very carefully adjusted, to
regulate the relative proportion of the various products. This apparatus
is able to produce about 75 or 80 per cent. of first-class alcohol, 10 to
15 per cent. of middle class alcohol, and 5 per cent. of ethers and 5 per
cent. of fusel oils, the alcohol produced being about 96∞ Cartier.
The alcohol is thus obtained in one single operation and with, it is
asserted, only a very small loss in rectification. The apparatus is
claimed to be so simple that it may be operated even by unskilled farm
labor. It is also claimed that purification by chemical treatment or
filtration is unnecessary with the Guillaume apparatus. It may be stated,
however, that the Guillaume system has many opponents.
The capacity of the rectifying apparatus has a good deal of influence
upon both the quantity and the quality of the spirit obtained. Besides
being much more difficult to manage, a small apparatus will not yield so
large a proportion of spirit as a more capacious one, nor will its
products be of equally good flavor. The proportion of alcohol which may
be obtained from a successful rectification is very variable; it depends
upon the nature of the spirit rectified, the method of extracting the
sugar, and the manner of conducting the distillation; it will also be in
inverse proportion to the quantity of fusel-oil contained in the raw
spirit. The average loss of pure alcohol during the process of
rectification is generally estimated at about five per cent.
In addition to the rectifying as above described, alcohol may be further
purified by filtration through charcoal, by chemical means or by
electrolysis. The last two methods have not so far been successful. The
chemicals used merely act to disguise the disagreeable taste or smell of
the spirit and do not really purify. They but substitute one impurity for
another. The agents used are many--sulphuric and nitrate acids, soaps,
oils and fats soda, lime and potash have each and all been tried, but
with no permanent success. As agents for disguising the taste of new and
raw spirits, alcoholic extracts of fruits have also been used.
Purification and aging by electricity has been tried many times and in
many different forms, but so far has not been commercially practicable.
Filtration still remains the best and simplest adjunct to the rectifier.
In small plants, a filter bed several feet in thickness of bone black
or beachwood or charcoal is used, laid upon a foundation of gravel in a
filtering tank. In the larger plants a series of these vats is used, the
charcoal being used in lumps varying from 1/4 to 1/2 inch in diameter.
Two different views of the purification by charcoal are held--one that
the charcoal purifies by chemical means, the other that it is purely a
physical filtration agent. After filtration the charcoal must be steamed
to recover the spirits retained therein and should be heated to a red
heat every now and then to cleanse and regenerate it.
CHAPTER VI.
MALTING.
Wheat, oats, rye, potatoes, and other amalyceous or starchy materials
contain starch insoluble in water and to render it soluble, and to change
the starch to maltose they must be mashed with a certain small proportion
of malt,--or grain in which germination has been artificially induced and
then interrupted at a certain stage. This increases the diastase
contained in the grain so germinated, and this diastase is able to
transform starch into soluble form. Hence, malted grain gives lightness
and liquidity to the wash, and prevents the starch falling to the bottom
of the mash tub or "back," and also prevents the starch falling to the
bottom of the still and consequent burning.
While all varieties of grain including rice are suitable for the
preparation of malt, barley is preferred to all others, and is most
commonly used.
=The best barley= for malting is that having the following
characteristics; a thin skin; a mealy interior; grains of a uniform size;
of the greatest weight; which has been stored for three months. Barley on
harvesting has but slight germinating power. The reason for the
uniformity in the grains lies in necessity of a uniform steeping of the
grain so that the period of germination shall be the same for the whole
mass.
Like all materials for distillation, the barley should be thoroughly
cleaned of impurities--not only dust, seeds and weeds, but fungi and
bacteria.
This may be partly accomplished in the ordinary fanning mills, usual on
farms, but a better machine would be a "tumbling box" of wire mesh. This
is inclined, so that grain put in the upper end, will pass downward to
the lower, being thrown about as the box or cylinder is rotated. The
dust, seeds, etc., fall through the meshes of the wire as do the smaller
grains. After this cleaning, the barley should be thoroughly washed. This
may be either done in the steeping vat itself--and the water afterwards
drawn off--or in special machines. If the barley be allowed to soak in
water for a day or two, the later washing will completely cleanse it.
This preliminary cleaning is most important as impurities reduce the
germinating power of the grain, as well as introduce bacteria inimical to
fermentation.
Washing in some instances is done by forcing compressed air into the
steeping tub, thus violently agitating and swirling the water therein,
and washing away the impurities. Another method is by passing the steeped
grains along a trough supplied with moving water, the trough being
provided with rotary agitators. Any fairly ingenious mechanic could
devise a capable cleansing machine. Care being taken that it shall not
injure the grains.
After cleansing, the barley should be steeped. For this purpose tanks of
metal or cement are to be preferred to wood. All vats should be kept
thoroughly cleaned by frequent scrubbing with lime water.
The barley placed therein should at all times be entirely covered with
fresh water to a depth of a few inches, and for the first few hours the
grains should be carefully stirred in order that no grain should escape
wetting. At the end of that time the still floating grains should be
removed.
In 36 or 48 hours the grain will usually be sufficiently steeped,--but
this varies with weather conditions. The warmer the water the quicker the
steeping, and in winter proper steeping may not be accomplished before
four or five days.
A simple test is to rub the grain strongly between the hands, If it is
entirely crushed, and no solid matter is left it has been steeped
sufficiently. Barley should be capable of compression lengthwise and the
hull should become easily detached. It should be easily bitten, and not
crack under the teeth. In order to prevent fermentation in summer, it is
well to renew the water a few times during steeping. Over steeping is
worse than under steeping.
After the barley is in proper condition the vat or tank is opened and the
water drained away. The draining should be complete, and therefore the
grain should be left to drain about 12 hours.
=Germinating.= The grain is now taken to the malting floor. In practice
it is well to locate the steeping vat above the malting floor, so that
the steeped grain may be run down on to the floor without inconvenience.
It is best to first spread the grains out on the floor to a depth of a
few inches in order that it may somewhat dry out. This is not necessary
when it has not been steeped to a great extent.
After 10 or 12 hours of drying, the grain is placed in a heap until warm
to the touch, which may occur in from 12 to 24 hours. It is then disposed
in a layer from eight inches to 20 inches thick. This is called the "wet
couch." The lower the temperature the thicker the couch should be. It
should be turned every six or eight hours in this stage.
The heat so germinated after 25 or 30 hours produces at the end of each
grain a small white rootlet. The grain in the middle of the layer is the
first to sprout, as it is the warmest, hence the couched grain should be
frequently turned so as to give all the grains a uniform heat, and a
uniform germination. At this period the grains beneath the surface are
dampish to the touch.
The height of the couch is now successively lessened to layers of from
six to two inches called "floors," the height of each floor of course
depending on the temperature, as before.
It is to be understood that the growing grain requires both dampness and
air, hence the "floor" should not be thinned so rapidly as to deprive it
of moisture, and the barley should be turned at least twice a day to give
each grain a proper aeration. During this period the small white rootlets
or radicals should be white and shiny. If they begin to fade, it is a
sign that they lack water and the grain should be sprinkled. Germination
usually requires from a week to ten days, or sometimes two weeks,
depending on the previous steeping, the quality of the grain and the
temperature. When the fibers or rootlets of the grain are about equal to
the length of the grain, germination is complete.
It used to be considered that malt was in its best condition in eight or
ten days. To-day, however, "long malt" is used,--requiring a germinating
period of twenty days, being frequently moistened and turned during this
time, and the temperature being kept at 65∞ F. This malt is very strong
in diastase.
The effect of germination is to produce a change particularly favorable
to mashing. The barley becomes sweetish, the gluten is partially
destroyed and what is left is soluble. Thus the fecula or starch is set
at liberty and free to be acted on by the yeast used in fermenting.
March is the best month in which to malt; and while the malt is best used
immediately, it can not be kept in its green state and must be therefore
dried for future use.
=Drying.= This is accomplished either in the air of a warm, dry room in
hot weather, or by means of a drying kiln. In the first process the malt
is spread in a thin layer and frequently turned. In the second the grain
is spread out in a layer from eight inches to a foot thick on the grain
floor of the kiln.
Beneath the grain floor a fire is maintained. In the beginning the
temperature of the drying floor should be about 85∞ F., but this is
increased gradually to about 104∞ F. until most of the moisture has been
removed. The heat is then raised to from 120∞ F. to 130∞ F., thus
completely drying the grain.
The germinated green or dried barley is called malt. It is of good
quality when the grain is round and flowery; when it crumbles easily and
when its taste is sweetish and agreeable. Pale malt or that which has
been hardly altered from its original color is the best for distillation.
Before the malt can be used it should be screened so as to remove the
rootlets.
Two hundred and twenty lbs. of barley should yield from 275 to 350 lbs.
of green malt, about 200 lbs. of air dried malt, and from 175 to 190 lbs.
of kiln dried malt.
In large plants malting is now so carried on that the steeping
germination and drying are all accomplished in one vessel or container,
by one continuous operation. This vessel is commonly in the form of a
drum of sheet iron, revolving at a very slow speed. Moist air is
introduced and the carbonic acid laden air withdrawn. After germination
the malt is dried by passing in dry air at the proper temperature.
As these systems are only adopted to large distilleries, using expensive
machinery, further reference to them is not considered necessary in this
volume.
Previous to use the malt must be finely ground or crushed either before
or after mixing with the materials to be mashed. It is not necessary or
advisable that the malt be reduced to flour. The use of malt with other
materials in order to form a fermentible mash, will be considered in the
chapters on specific mashes.
CHAPTER VII.
ALCOHOL FROM POTATOES.
In certain countries, as for instance Germany and France, potatoes form
the greatest source of alcohol, particularly for industrial purposes.
With the possible exception of corn and beets they will probably be most
used in America.
The best potatoes for distilling are those which are most farinaceous
when boiled. In other words, those which are "mealy" and most appetizing.
These give the largest yield of alcohol per bushel. The best season of
the year in which to use potatoes is from October to March, when they
germinate.
The potatoes should be kept in dry cellars, and at even temperatures,
warm enough to prevent freezing and yet not so warm that they will rot or
sprout. Diseased potatoes may however be used, if they have not been
attacked by dry rot, though they are not so easily worked. Frosted
potatoes may be also used, but they must not have been completely frozen.
Before being steamed, the potatoes should be washed, either by hand or by
a machine, care being taken to remove all stones, clods of earth, and
other foreign substances which might impede the subsequent operations.
There are three main methods of saccharifying the fecula or starch of the
potato. The first and most important by reducing the tubers to a pulp,
and malting the entire mass. The second and third, by rasping the
potatoes and so separating the fecula or starch grains from the mass, and
then making a thin liquor or wash containing this fecula.
Originally, in the first process, the washed potatoes were submitted to
the action of boiling water, but later cooking by steam at a temperature
of 212∞ F. was used, as being much more convenient to handle and more
effective in action. The object of steaming is to break the coating and
reduce the contents thereof to a pasty condition, wherein the starch is
more effectively acted on by the malt and yeast. Ordinary steaming does
not, however, render the pulp sufficiently pasty; some of the starch
remains undissolved and is lost, hence in the modern practice, steam is
turned into the steaming vat under a pressure of three or four atmosphere
(45 to 60 lbs. to the square inch).
High pressure steaming will be later described but the simple and older
method of mashing and apparatus therefor, used prior to 1870, was as
follows:
Fig. 41 shows a section of a steaming vat. This consists of a conical
wooden tub _H_ provided at its top with a suitable cover _O_ having a
trap or door _P_ for putting in the potatoes. This as shown, consists of
a hinged lid, having a button _p_ or other fastening means. This lid and
cover should be of course steam tight, and it would be better to have it
clamped down by a screw clamp than held by a button.
Somewhat above the bottom of the vat, a steam inlet pipe _I_ enters,
connected at its other end by a coupling _i_ with a suitable steam
generator (see Fig. 43), Preferably the outlet of this pipe is screened
by a perforated plate _M_ so that it may not be clogged by the pulp. It
is also best that a filling piece be placed at the junction of the bottom
with the sides in order that there be no sharp corner from which the pulp
may not be easily cleaned out.
[Illustration: FIG. 41.--Steaming Vat for Potatoes.]
The bottom of the vat may either have a discharge door at the side as in
Fig. 44 or at the bottom, as in Fig. 41.
An under side view of the latter construction is shown in Fig. 42. The
bottom of the vat is made in two parts or doors _J K_. These are held
closed by a transverse bar _L_ inserted at its end into a stirrup _l¥_
and supported at its other end by a button _l_, or other means.
While various forms of steam generators may be used, Fig. 43 shows a
simple construction well adapted to the needs of a small distillery. _D_
designates the brick work of a furnace, and _A_ the boiler. This is so
set that an annular space _E_ surrounds the sides of the boiler, through
which the products of combustion must pass.
[Illustration: FIG. 42.--Bottom of Steaming Vat.]
The head of the boiler is connected by a pipe _B_ and collar _b_ to the
steam inlet pipe _I_ of the steaming vat, heretofore described, as by the
collars _b i_.
A filling tube _C_ enters the boiler and projects nearly to the bottom,
and the water outlet-pipe _F_ with cock _f_ leads off from the upper
water line. The tube _C_ forms also a safety valve, for if the steam
pressure becomes too great in the boiler and connected vat, it will force
water up and out through the tube. If, however, the water falls below the
level of the lower end of the tube, steam will issue and warn the
attendant that water is too low. It would be best however, to provide a
steam gauge, whereby the pressure of steam in the boiler and vat could be
accurately indicated.
[Illustration: FIG. 43.--Steam Generator.]
It is to be noted that when steamed the potatoes will swell and occupy
more space and that the steam vat should therefore not be much more than
two-thirds filled with potatoes.
With the steaming vat above shown, the potatoes are delivered mixed with
a considerable quantity of water, but a better plan is to have a
perforated false bottom to the tub, whereby the condensed water may be
carried away, the steamed potatoes remaining behind.
[Illustration: FIG. 44.--Potato Steamer and Crusher.]
Two hours of steaming should reduce the potatoes to proper condition,
which may be tested by introducing a pointed iron rod through a suitable
aperture, normally kept closed. If the rod passes freely inward, the
potatoes are done and may be discharged into the crusher, shown in Fig.
44. In this Fig. the steaming vat _A_ is shown mounted above the crusher.
A pipe _B_ with cock _b_ leads to the steam generator. The steamed
potatoes are shoveled out through the door _a_, which is usually held
closed by means of the clamps or buttons _a¥ a¥¥_.
=The crusher= consists of a hopper _C_ whose bottom fits closely against
two adjacent smooth faced rolls _H I_ of iron. These are driven by gears
_D E_. The shafts of these gears have cranks _d d_ whereby it may be
operated. These gears are unequal so that the rolls shall move at
different speeds, and thus one will have a grinding action against the
face of the other. A counter weighted scraper _e_ bears against the face
of the roll.
The crushed potato pulp passes between the rolls and into a bin beneath,
having adjustable walls made of boards _F_, sliding in suitable guides
_f_, from which the pulp may be shoveled into the mashing tank or "back."
The crusher might, however, be arranged to deliver immediately into the
mashing tank, if the latter is provided with means for stirring the
delivered pulp.
The pulp or paste thus made is now placed in a vat, holding about 650 to
850 gals., in which the saccharification takes place. About 2200 lbs. of
the crushed potatoes and 155 lbs of broken malt are introduced, and
immediately afterwards water is run in at a temperature of about 97∞ F.
to 104∞ F., the contents being well stirred with a fork meanwhile. The
vat is then carefully closed for half an hour, after which boiling water
is added until the temperature reaches 140∞ F., when the whole is left
for three or four hours. The process of fermentation is conducted in the
same vat. Alternate doses of cold and boiling water are run in upon the
mixture, until the quantity is made up to 700 or 775 gallons, according
to the size of the vat, and so as finally to bring the temperature to 75∞
F. or 79∞ F. Five and a half to six gallons of liquid brewer's yeast are
then added, and fermentation speedily sets in. This process complete, the
fermented pulp is distilled in the apparatus devised by
Cellier-Blumenthal (see Fig. 15) for distilling materials of a pasty
nature; the product has a very unpleasant odor and taste.
The process above described is the old method of pulping the potatoes by
using steam. Under the modern method, however, and with modern apparatus,
in preparing potatoes for distillation in large quantities, the steaming
of the material is accomplished at one time and under a high steam
pressure. The apparatus is also used for the preparation of corn,
potatoes and other starch-containing substances.
There are many apparatuses which have been devised for the purpose, but
the principle on which they work is practically the same in all cases.
They comprise a closed tank, fitted with stirrers, agitators, or other
means for mixing and comminuting the contents, means for admitting steam
under pressure, means for cooling the mixture to the proper mashing
temperatures, and means for forcing the steamed material out of the tank.
[Illustration: FIG. 45.--Bohn's Steamer and Crusher.]
=The Steamer.= One of the earliest forms of steamer was that of
Hallefreund devised in 1871, and adapted for working on a large scale. A
modified form of the apparatus known as Bohn's steamer and masher is
illustrated in Fig. 45. This comprises a steaming cylinder _A_, having a
securely closed opening _D_ for the introduction of the potatoes.
Centrally through the cylinder passes a hollow shaft _B_, which is
rotated by the power pulley _K_. Hollow arms _b_ project radially from
the shaft _B_. These act as mixers of the mash and as coolers. The shaft
_B_ at one end is connected to a cold water supply pipe _M_ as by a
coupling _C_, the supply pipe being provided with a cock. _E_ designates
a discharge opening for the mash. A pipe _F_ provides for the entrance of
steam into the cylinder. _G_ is a pipe through which malt is put in to be
mixed with the pulp. _L_ is a steam gauge and _J_ a safety valve. _H_
designates a water pipe. For the relation of the steamer to other
apparatus, see Fig. 1.
In operation the potatoes are placed in the cylinder _A_ and submitted to
the action of steam at about 46 lbs. to the square inch, and at a
temperature of from 266∞ F. to 275∞ F.
When disintegrated, the steam is blown off, and the potatoes crushed by
rotating the stirring shaft. As the pulp must be reduced from 275∞ F. to
149∞ F., the mashing temperature, cold water is forced into the stirrer
which chills the blades and quickly cools the mass.
In the vacuum mash cooker shown in Fig. 1, the steaming cylinder is
partly filled with hot water at 140∞ F. to 150∞ F. The potatoes to be
mashed are fed into the cylinder whole. The steamer is then closed and
steam admitted while the mash is stirred until a pressure of 65 pounds is
reached, when the dissolution of the starch is complete. The steam is
then exhausted and the temperature reduced to 212∞ F. To reduce this
temperature to the proper saccharifying point of 145∞ F., the hot air is
exhausted.
Barley malt meal in the proportion of 6 to 10 per cent. is used. This has
been previously mixed with cold water in the small grain masher. The malt
is admitted to the cylinder and thoroughly mixed with the potato, when
the mixture is withdrawn into a drop tub, where it is still further
stirred. It is then cooled as described on page 15 and then fermented.
While the crushed potatoes are being cooled and stirred, a mixture of
green malt with water is prepared in an adjacent vat, and when the pulp
in the cylinder has been reduced to 149∞ F. the malt mixture is
introduced into the cylinder through the pipe _G_, and thoroughly mixed
with the crushed potatoes. The mass is now left to saccharify; the
stirrer being operated at intervals throughout this period. This machine
might be readily modified so that the steam should enter through the
stirrers, by tubes attached to the arms, then the steam may be shut off
and cold water sent into the arms themselves to cool the mash.
A variety of steamer used in various forms and modifications in all the
larger distilleries, is known as the Henze steamer, Fig. 2. In this,
there are no stirrers. The cylinder is conical, and has steam pipes
leading to the interior. At the end of its cone-shaped bottom it
terminates in a blow-off tube, having in it a grate formed of sharp-edged
bars. In operation, steam is introduced at a pressure of one to two
atmospheres until the potatoes are cooked. More steam is then suddenly
admitted at high pressure and the softened potatoes forced through the
grating at the bottom and into the mashing apparatus in a finely divided
state.
In steaming under pressure it is best that the safety valve be so
regulated that the steam will constantly blow off as this action keeps
the potatoes in motion and facilitates disintegration. Care should also
be taken to see that everything about the apparatus is in good condition,
as in working under the high pressures used in the last apparatus there
is liability of explosion. Rust should be particularly guarded against.
With this apparatus a preparatory mash vat is used into which the
contents of the steamers are blown out, malt and water to form milk
having been previously let into the mash vat. Blowing out is accomplished
in 45 or 50 minutes at 130∞ F. and about one-sixth of the charge in the
steamer is retained in the steamer. The mash in the vat is stirred and
cooled and the remainder of the mash blown in raising the temperature to
145∞ F. when the mash is left to stand from half an hour to an hour. With
heavy mashes, rich in sugar, even higher temperatures than 145∞ F. can be
used for saccharifying.
The processes of crushing and saccharifying, above referred to, which are
almost entirely used to-day, require steam. The following methods provide
for the isolation of the fecula or starch, without steam and the
production of a wash of a more watery consistency, therefore easier to
handle in ordinary stills, and with less liability to burn.
Two operations are necessary by this method: First, rasping, or reducing
the potatoes to a finely crushed and pulpy condition by means of a
machine described in the chapter on Beet Mashing; and second, the
separation of the fecula.
To this latter end the potato pulp is placed on a sieve, having side
walls and net work of horse-hair, which is placed over a suitable tub.
Water is run gradually through the pulp and sieve, while the pulp is
rubbed up by hand. When the water comes through clear, then all the
fecula of the pulp has been washed out, and the refuse left in the sieve
can be thrown aside or used as a food for cattle.
=For a mashing tub= of say about 32 bushels capacity, the fecula from
about 800 lbs. of potatoes is used. This is deposited in the mash tub
with sufficient cold water to form a fairly clear paste. About twice as
much water as fecula will bring the paste to proper consistency. This
mixture should be constantly stirred as otherwise the fecula will sink to
the bottom. About 40 gallons of boiling water are then added gradually.
The mixture has at first a milky appearance, but at the last becomes
entirely clear.
This liquid is mashed with about 45 lbs. of malted barley or Indian corn,
ground into coarse flour. In ten minutes the mixture will be completely
fluidified. It is then left to subside for three or four hours when it
will have acquired a sweetish taste and be what is termed as "sweet
mash." The fluid is then further diluted by the addition of sufficient
water to give about 290 gallons of wash. Two or three pints of good yeast
will bring this mixture to a ferment.
A less laborious method of accomplishing the same result is that at one
time used in English distilleries. In this a double bottom tub is used,
something like that shown in Fig. 41, the upper bottom of which is
perforated, and raised above the solid lower bottom. A draw-off cock
opens out from the space between the two bottoms.
Assuming that the tub is of 220 gallons capacity, then from 2 to 20 lbs.
of chaff are spread over the perforated bottom and pulp from 800 lbs. of
raw potatoes placed on that. This is thoroughly drained for half an hour,
through the draw-off cock. The pulp is then stirred while from 90 to 100
gallons of boiling water are added gradually. The mass then thickens into
a paste. The paste is mashed with about 65 lbs. of well steeped malt,
and the liquid left to subside for three or four hours. It is then
drained off through the perforated bottom into a fermenting back or tub.
For this amount of material the back should be of about 300 gallons
capacity.
=The leavings= left in the preparatory tub still contain considerable
starch, and after they are well drained they should be mixed with from 50
to 55 gallons of boiling water. The mixture is then agitated and drained
off into the fermenting back. The sediment left is again sprinkled with
water, this time cold, which is drained off into the back. This
completely exhausts the husks left on the upper bottom. By this process
200 lbs. of potatoes should produce something over 12-1/2 gallons of
spirit.
The objection to the last method described is that the spirit so obtained
is unpleasant to taste and smell, but this would probably not be an
objection for industrial uses.
The only means of obtaining alcohol of good quality from potatoes is to
extract the starch separately and then convert it into sugar. This
saccharification of the starch may be accomplished by sulphuric acid or
by the action of diastase.
By the first of these methods the potatoes are disintegrated in such an
apparatus as the Bohn steamer described on page 118. A mixture is made of
one-third potatoes, two-thirds water, and onetenth part of sulphuric
acid. The mixture is steamed for six or eight hours under pressure. The
mash is then cooled and the acid neutralized by milk of lime. It is then
fermented.
By the second and preferable method, dry or wet potato starch is used,
which is malted, and the saccharine solution fermented with yeast. The
proportions and method for a vat of say 800 gallons capacity are as
follows:
Two hundred and sixty-five gallons of water are mixed with 1100 lbs. of
dry or 1650 lbs. of moist starch. This mixture is well agitated, and 450
gallons of boiling water run in, together with 165 lbs. of malt. The
whole is then stirred energetically and left to saccharify for three or
four hours. The saccharine solution thus formed must be brought to 6∞ or
7∞ Baume, at a temperature of from 71∞ to 75∞ F. To this is then added
1-1/100 lbs. of dry yeast for every 220 gallons of "must." Fermentation
is soon established and usually occupies about 36 hours. After remaining
at rest for 24 hours the "must" is distilled. From each 220 lbs. of
starch there should be a yield of about nine gallons of alcohol,
at 90∞ F.
The fermentation of the potato mash is carried on as described in Chapter
II. For the preparation of malt see Chapter VI.
CHAPTER VIII.
ALCOHOL FROM GRAIN--CORN, WHEAT, RICE, AND OTHER CEREALS.
The different cereals constitute a very important source of alcohol in
all countries, particularly of course for use in the manufacture of
whiskey and gin.
All cereals contain an abundance of starchy substance which under the
influence of diastase,--that is, malt,--is converted into fermentible
sugar. The quantity of sugar and hence the yield of alcohol differs
widely. The following table shows the results obtainable by good
workmanship.
220 lbs. Wheat gives 7.0 gallons pure alcohol
" " Rye " 6.16 " " "
" " Barley " 5.5 " " "
" " Oats " 4.8 " " "
" " Buckwheat " 5.5 " " "
" " Corn (Indian) " 5.5 " " "
" " Rice " 7.7 " " "
In addition to these there are other raw materials containing starch
which are sometimes used, as millet (55 per cent starch), chestnuts (28
per cent.), and horse chestnuts (40 per cent.). The last is very
difficult to work however.
Rice, wheat, rye, barley and corn are more frequently employed than other
grains. Wheat gives a malt which is as rich in diastase as barley. Barley
and buckwheat are added to these in some proportions. Oats, owing to
their high price, are rarely used. Rice, of all the grain is the most
productive to the distillers, but on account of its value as a food is
not much used for the production of alcohol, unless damaged. Corn is the
cereal most largely used for the production of industrial alcohol.
Great care should be exercised in making choice of grain for fermentation
where the best results are desired. Wheat should be farinaceous, heavy
and dry. Barley should be free from chaff, quite fresh and in large
uniform grains of a bright color (see Malting, Chapter VI).
Rice should be dull white in color, slightly transparent, without odor,
and of a fresh, farinaceous taste.
The flour or farinaceous part of grain is composed of starch, gluten,
albumen, mucilage, and some sugar. The following table gives the
proportions of these substances in the commonest grains.
Under certain conditions the albumen or gluten in the grain has the power
of converting starch into saccharine matter. This is better effected by
an acid such as sulphuric acid, or by a diastase. This latter substance
is a principle developed during the germination of all cereals but
especially of barley. It has the property of reacting upon starchy
matters, converting them first into a gummy substance called dextrine,
and then into glucose or grape sugar, see Chapter II.
The action of diastase upon starch or flour made into a paste is
remarkable, 50 grains of diastase being sufficient to convert 220 lbs.
(100 kilogrammes) of starch into glucose. The rapidity of this change
depends on the quantity of water employed, and the degree of heat
adopted in the operation.
TABLE IV.
PROPORTIONS OF STARCH, GLUTEN, ETC., IN PRINCIPAL GRAINS.
Column A = Grains.
Column B = Starch.
Column C = Gluten and other Azotized Substances.
Column D = Detrine, Glucose and similar Substances.
Column E = Fatty Matter.
Column F = Cellulose.
Column G = Inorganic Salts. (Silica, Phosphates &c.)
-----------+-- ----+--------+-------+-----+---------+------
A | B | C | D | E | F | G
-----------+-------+--------+-------+------+--------+------
Wheat }| 65.99 | 18.03 | 7.63 | 2.16 | 3.50 | 2.69
(average }| | | | | |
of five }| | | | | |
varieties)}| | | | | |
Rye | 65.65 | 13.50 | 12.00 | 2.15 | 4.10 | 2.60
Barley | 65.43 | 13.96 | 10.00 | 2.76 4.75 | 3.10
Oats | 60.59 | 14.39 | 9.25 | 5.50 7.06 | 3.25
Indian Corn| 67.55 | 12.50 | 4.00 | 8.80 | 5.90 | 1.25
Rice | 89.15 | 7.05 | 1.00 | 0.80 | 1.10 | 0.90
-----------+-------+--------+-------+------+--------+------
Inasmuch as barley germinates very readily, and develops a larger
proportion of diastase than any other grain, except wheat, it is
generally used as a producer of diastase. Barley germinated according to
proper methods is called malt, and its preparation is fully described in
Chapter VI.
There are many methods of preparing grain for fermentation, but all use
at least two of the following operations:--grinding, gelatinizing,
steeping, or steaming, mashing saccharifying.
=Grinding.= Where cookers or the Henze steamers are not used every form
of grain should be crushed or ground into a coarse flour. This is in
order that the starchy interior may be easily acted on by the diastase.
If the grain is not to be mixed with malt later it must be ground more
finely so that it may be thoroughly penetrated by the water. The grains
should not be ground except as required, as ground grain is liable to
heating and consequent loss of fermentability, and is also liable to
become musty, in which condition it loses much of its fermentability.
=Steeping.= This operation is best carried on in vats or tanks of iron or
cement, for the reason that wood absorbs impurities, which are
communicated to the grain, thus lessening its germinative power. Wooden
vats should be thoroughly scrubbed after use, and be kept continually
whitewashed. The steeping tub should hold about two-thirds more than the
amount of ground grain to be steeped.
Steeping is affected by pouring on to the crushed grain hot and cold
water in such quantity that after 10 minutes or so of brewing the mixture
will have a temperature of 75∞ to 95∞ F.
This warmth makes the water more penetrating. The water should not be
poured in all at once, but a little at a time, until the grain is covered
to a depth of three or four inches. Care should be taken not to let the
temperature get too high, not above 95∞ F., as a temperature above that
point kills the germinating power.
The mixture of crushed grain and water is now stirred for 10 minutes and
then left to subside for half an hour. It is then stirred again and the
mixture left to steep for 30 or 40 hours, depending on the temperature of
the atmosphere, the dryness of the grain, and the character of the water.
In very warm weather the water should be changed every few hours by
running it off through a hole in the bottom of the tub and running in
fresh at the top. This prevents fermentation setting in prematurely.
When the grain swells, and yields readily between the fingers it has been
sufficiently steeped, and the water is run off. This is an old method of
gelatinizing grain, but a better is by the use of cookers or high
pressure steamers as described for potatoes.
=Mashing.= This consists in mixing the coarse flour with malt and then by
means of certain operations and mechanisms bringing it to a condition
most favorable to fermentation through the action of yeast. The mixing of
the raw flour with barley or other malt effects the conversion of the
starch of the grain into maltose. The yeast afterwards converts this
maltose into sugar.
=Saccharifying.= To effect the action of the diastase of the malt on the
grain, in the old methods, boiling water must be poured into the vat
until the temperature of the mass reaches about 140∞ to 168∞ F., the
whole being well stirred meanwhile; when this temperature has been
reached, the vat is again covered and left to stand for four hours,
during which time the temperature should, if possible, be maintained at
140∞ F., and on no account suffered to fall below 122∞ F., in order to
avoid the inevitable loss of alcohol consequent upon the acidity always
produced by so low a temperature. In cold weather the heat should of
course be considerably greater than in hot. It should be also remarked
that the greater the quantity of water employed, the more complete will
be the saccharification, and the shorter the time occupied by the
process.
Having undergone all the above processes, the wash is next drawn from the
mash tub into a cistern, and from this it is pumped into the coolers.
When the wash has acquired the correct temperature, viz., from 68∞ to 78∞
F., according to the bulk operated upon, it is run down again into the
fermenting vats situated on the floor beneath. Ten to twelve pints of
liquid or 5-1/2 to 6-1/2]** fraction] lbs. of dry brewer's yeast are then
added for every 220 lbs. of grain; the vat is securely covered, and the
contents are left to ferment. The process is complete at the end of four
or five days, and if conducted under favorable conditions there should be
a yield of about 6-1/6 gallons of pure alcohol to every 220 lbs. of grain
employed.
There are a number of different methods of mashing, having each its
advantages, and applicable to particular varieties of grain.
We will first consider the mashing of the steeped grain in general by one
of the older and simpler processes.
The grain to be mashed, which has been ground and steeped as before
described, is mixed with malt in the proportion of four to one, or even
eight to one. In addition, three or four pounds of chaff to every hundred
or so pounds of steeped grain should be used.
=Mash.= Water is then run into the mash tub in the proportion of about
600 gallons to each 60 bushels of grain. Its temperature should be
between 120∞ and 150∞ F. During the entrance of water, the mass is well
stirred so as to cause the whole of the grain to be thoroughly soaked and
to prevent the formation of lumps. It is best to add the grain to the
water gradually and to stir thoroughly.
To this mass about 400 gallons of boiling water is gradually added to
keep the temperature at about 145∞ F. During the addition of the boiling
water the mash should be continually stirred so that the action of the
water shall be uniform. This operation should last about two and one half
hours. The vat should be then covered and left to stand from
three-quarters to one hour for saccharification.
Another method of saccharifying is to turn boiling water gradually into
the mash tank until the mixture has acquired a temperature of from 140∞
to 180∞ F. The mass is thoroughly stirred and the tub is covered and left
to subside for from two to four hours, during which time the temperature
should not be allowed to fall below 120∞ F. A small tub needs more heat
than a larger tub, and more heat is required in winter than in summer.
A convenient method of regulating the temperature of the mash tank, would
be by a coil of pipes on the bottom. This would be connected by a two-way
cock to a steam boiler and to a source of cold water. Heat should never
be carried over 180∞ F., and the best temperature is from 145∞ to 165∞ F.
The greatest effect of the diastase of the malt upon the gelatinized
starch is at 131∞ F. For ungelatinized starch this is not great enough,
hence the greater part of the mashing is carried on at the lower
temperature and only towards the end should the temperature be raised to
the maximum 150∞ F.
Every distiller uses his own judgment as to the amount of the mashing
water used, its temperature, the length of time during which the mash
rests, and the length of time for saccharification.
Saccharification may be recognized by the following signs: The mash loses
its first white mealy look, and changes to dark brown. It also becomes
thin and easily stirred. The taste is sweet and its odor is like that of
fresh bread.
Corn and other grain may be mashed conveniently in such an apparatus as
that described on page 10, as used for potatoes the steam being
introduced under pressure.
The water is first placed in the steamer. Steam is introduced into the
water and it is brought to a boil. The corn is then introduced gradually,
the steam pressure increased to its maximum, and the mass blown out as
described in Chapter VII. Hellefreund's apparatus (see page 118) may also
be used with ground corn.
The corn or grain not previously crushed or ground is introduced into a
steamer in the proportion of 200 lbs. of corn to 40 gallons of water. The
steamer should have about 100 gallons of steam space for this amount.
The mashes described above are thick, more or less troublesome to distil,
and only simple stills can be used. By the following method a clear
saccharine fluid or wort can be obtained.
=A mash vat= is used having a double bottom. The upper bottom is
perforated and between the two bottoms is a draw-off pipe and a pipe for
the inlet of water.
Upon the upper perforated bottom is first placed a layer of between two
and three pounds of chaff. Upon this is turned in a mixture of 400 lbs.
corn and malt in the proportions of 1/5 malt to 4/5 grain. Eighty-seven
gallons of water at a temperature of from 85∞ to 105∞ F. is then let in
to the bottom, while the mixture is thoroughly agitated for 10 minutes.
It is then left to subside for half an hour.
After this steeping process, the mass is again agitated while 175 gallons
of water at 190∞ F. are let into the tub while the mass is continually
and thoroughly stirred by mechanical stirrers. Brewing lasts for half an
hour, and the liquid is then left to stand for seven hours.
At the end of this period the grain is covered by clear liquid which is
drained off through the draw-off cock into the fermenting back.
To the contents left in the steeping tank 135 gallons of boiling water
are added as before and the liquid therefrom drawn into the fermenting
back.
It usually requires three infusions to extract the whole of the
saccharine and fermentiscible matters contained in the grain. In some
places, it is customary to boil down the liquors from the three mashings
until they have acquired a specific gravity of about 1.05, the liquor
from a fourth mashing being used to bring the whole to the correct degree
for fermentation, the liquors from the third and fourth being boiled down
to the same density and then added to the rest. In a large Glasgow
distillery, the charge for the mash tubs is 29,120 lbs. of grain together
with the proper proportion of malt. Two mashings are employed, about
28,300 gallons of water being required; the first mashing has a
temperature of 140∞ F., and the second that of 176∞ F. In Dublin the
proportion of malt employed is only about one-eighth of the entire
charge. One mashing is employed, and the temperature of the water is kept
at about 143∞ F. The subsequent mashings are kept for the next day's
brewing.
By this process the grain is entirely deprived of all fermentible
substances which have been carried away in a state of liquid sugar.
The whole operation of preparing and saccharifying grain is to-day
carried on in steamers, such as described on page 11, and cooking
apparatus such as shown in Fig. 1, or in the Henze high pressure steamers
and preparatory mash vats described in Chapter II.
In steaming grain without pressure, the finely crushed grain is poured
slowly into a vat previously nearly filled with water at a temperature of
about 140 degrees F. A little less than half a gallon of water is used
for each pound of grain. Care must be taken to stir the mass constantly
to prevent lumping. When all the corn is mixed in, steam is allowed to
enter and the temperature raised to about 200 degrees F. It should be
left at this temperature for an hour, or an hour and a half, when the
temperature is reduced to 140∞ F. when about 10 per cent. of crushed malt
is added and the temperature reduced to 68∞ F. by means of suitable
cooling devices.
When steam cookers are used, the cylindrical boiler is first filled to
the proper degree with water at a temperature of 140∞ F. The meal is then
let in gradually being constantly stirred the while. The boiler is then
closed and steam gradually let in while the mass is stirred until a
pressure of 60 pounds and a temperature of 300∞ F. has been reached. The
starch then becomes entirely gelatinized, the pressure is relieved, and
the temperature reduced to 212∞ F. and then rapidly brought to 145∞ F.
The malt is added mixed with cold water, at such a stage before the
saccharifying temperature is reached that the cold malt and water will
bring it to 145∞ F. The malt is stirred and mixed with the mash for five
or ten minutes and the mixed mass let into a drop tub when
saccharification is completed. It is then cooled as described.
When the Henze steamers are used the grain may be treated in either the
whole grain or crushed, as the high pressure to which it is subjected and
the "blowing out" act to entirely disintegrate it. In this mode of
operation, water is first let into the steamer and brought to a boil by
the admission of steam. The grain is then slowly let into the apparatus.
The water and grain should fill the steamer about two thirds full. The
steamer is left open and steam circulated through the grain and water
for about an hour, but without any raising of pressure. This acts to
thoroughly cook and soften the grain.
When sufficiently softened the steam escape cock in the upper part of the
steamer (see Fig. 2) is regulated to allow a partial flow of steam
through it and a greater flow of steam is admitted through the lower
inlet. This keeps the grain in constant ebullition under a pressure of 30
lbs. or so. After another period of an hour the pressure in the steamer
is raised to 60 lbs. at which point it is kept for half an hour, when the
maximum steam pressure is applied, and the greater portion of the
disintegrated mass blown out into a preparatory mass tub, into which malt
has been placed mixed with water. The blowing out should be so performed
that the temperature in the mass in the tubs shall not exceed 130∞ F. The
mass is stirred and cooled and then the remainder of the mass in the
steamer admitted to the tub which should bring the temperature of the
mass up to 145∞ F. It is kept at this temperature for a period varying
from half an hour to one and one-half hours and is then cooled to the
proper fermenting temperature.
Another method of softening corn so that its starch is easily acted upon
by the diastase of the malt is to steep it in a sulphurous acid solution
at a temperature of about 120∞ F. for from fifteen to twenty hours. The
mass is then diluted to form a semi-liquid pulp and heated to about 190∞
F. for an hour or two during which the mass is constantly stirred. The
malt is then added, the mass is saccharified, cooled and then fermented.
Another method is to place mixed grain and hot water in a cooker of the
Bohn variety (Fig. 45). After half an hour of stirring and cooking under
ordinary pressure, the steam pressure is raised to 45 lbs. This is kept
up for from two to three hours when the grain is reduced to a paste.
Concentrated muriatic acid equal to 2-1/2 per cent of the weight of
grain is then forced in, under steam pressure. In half an hour the grain
will be entirely saccharified and ready for fermenting.
CHAPTER IX.
ALCOHOL FROM BEETS.
=Cultivation.= The beetroot (_Beta vulgaris_), indigenous to Europe, is
cultivated in France, Germany, Belgium, Holland, Scandinavia, Austria,
Russia, and to a very small extent in England and New Zealand, and to a
very large extent in the United States and Canada. There are many
varieties. The most important to the sugar-maker is the white Silesian,
sometimes regarded as a distinct species (_B. alba_); it shows very
little above ground, and penetrates about 12 in.; it has a white flesh,
the two chief forms being distinguished by one having a rose-colored skin
and purple-ribbed leaves, the other a white skin and green leaves. Both
are frequently grown together, and exhibit no marked difference in
sugar-yielding qualities.
Good sugar-beets possess the following broad characteristics: (1) Regular
pear-shaped form and smooth skin; long, tapering, carrot-like roots are
considered inferior; (2) white and firm flesh, delicate and uniform
structure, and clean sugary flavor; thick-skinned roots are spongy and
watery; those with large leaves are generally richer; (3) average weight
1-1/2 to 2-1/2 lbs., neither very large nor very small roots being
profitable to the sugar-manufacturer; as a rule, beets weighing more than
3-1/2 lbs. are watery, and poor in sugar; and roots weighing less than
3/4 lb. are either unripe or too woody, and in either case yield
comparatively little sugar; the sp. gr. of the expressed juice, usually
1.06 to 1.07, even reaching 1.078 in English-grown roots, indicating over
14 per cent. of crystallizable sugar, is the best proof of quality; juice
poor in sugar has a density below 1.060; (4) in well-cultivated soil, the
roots grow entirely in the ground, and throw up leaves of moderate size.
=Composition of the Roots.= Internally the root is built up of small
cells, each filled with a juice consisting of a watery solution of many
bodies besides sugar. These include several crystallized salts (mostly of
which are present in minute traces only), such as the phosphates,
oxalates, malates, and chlorides of potassium, sodium, and calcium, the
salts of potash being by far the most important; and several colloid
bodies (albuminous [nitrogenous] and pectinous compounds); as well as a
substance which rapidly blackens on exposure to the air. The greater part
of the sugar in ripe beets is crystallizable, and, when perfectly pure,
is identical in composition and properties with crystallized cane-sugar;
but it is more difficult to refine this sugar so as to free it from the
potash salts, and commercial samples have not nearly so great sweetening
power as ordinary cane-sugar. Beets contain no uncrystallizable sugar;
the molasses produced in beet-sugar manufactories is the result of
changes which cannot be entirely avoided in extracting the crystallizable
sugar.
=Soil.= The best soil for beets contains a fair proportion of organic
matter, is neither too stiff nor too light, and crumbles down into a nice
friable loam; it must be capable of being cultivated to a depth of at
least 16 in. The subsoil should be thoroughly well drained, and rendered
friable by autumn-cultivation and free admission of air. A deep friable
turnip-loam, containing fair proportions of clay and lime, appears to be
the most eligible land for sugar-beets. Lime is a very desirable element.
Well-worked clay-soils, especially calcareous clays, are well adapted, if
properly drained and of sufficient depth. Peaty soils and moorlands are
quite unsuitable, as well as lands which are too dry, like the thin
gravelly soils resting on siliceous gravel sub-soils, or too wet and
cold, like many of the thin soils above impervious chalk marl.
Speaking generally, the best soils for sugar-beet are precisely those on
which other root-crops can be grown to perfection, that is, land which is
neither too heavy nor too light, which has a good depth, is readily
penetrated by the roots, and naturally contains lime, potash, clay, and
sand, as well as organic matter, is such proportions as in good friable
clay-loams. An analysis of the soil should be made previous to planting
it with the sugar-beet, as the salts presented in solution in the soil
will pass into the juice, and greatly interfere with the processes of
sugar manufacture. Certain soils may be at once indicated as unsuitable;
they are clover-land, recent sheep-pastures, forest-land grubbed during
the preceding 15 years, the neighborhood of salt works, volcanic and
saline soils of all kinds. The beet requires a certain supply of potash
and soda salts in the soil, but if these are present in excess, as in
recent forest-land, the juice does not work well, nor give its proper
yield of sugar.
=Manures.= Sugar-beets should be grown with as little farmyard manure as
possible; when dung has to be used, as in the case of very poor soils, it
should be applied in autumn, or as early as possible during the winter
months. The effect of heavy dressings of animal nitrogenous matters or
ammoniacal salts, is to produce abundance of leaves, and big watery
roots; the latter are comparatively poor in sugar, and contain potash
salts derived from the animal matters, which greatly interfere with the
extraction of sugar in a crystallized state. Common salt, and saline
manures in general, though useful in moderate doses (224 lbs. to 336 lbs.
per acre on light soils), should be avoided on the majority of soils, for
sugar-beets grown on soils highly manured with common salt produce juice
largely impregnated with salt, which is dreaded by the manufacturer even
more than albuminous impurities, and nearly as much as excess of potash
salts.
If the land is in good condition, containing sufficient available
nitrogen to meet the requirements of the crop, neither guano nor sulphate
of ammonia should be used. They largely increase the weight of the
produce per acre; but heavy crops are generally poor in sugar, and
furnish a juice that presents much difficulty to the manufacturer. If the
land is very poor, and if farmyard manure cannot be obtained and be
applied in autumn, 336 to 448 lbs. of Peruvian guano, or 224 lbs. of
sulphate of ammonia, mixed with 224 lbs. of superphosphate of lime, per
acre, may be sown broadcast in autumn, and 224 lbs. more of
superphosphate may be drilled in with the seed in spring. Superphosphate
of lime and bones are excellent for sugar-beets, and never injure the
quality of the crop, like the indiscriminate use of ammoniacal manures.
On light soils, in which potash is often deficient, the judicious use of
potash salts has been found serviceable, but only in conjunction with
superphosphate and phosphatic guanos.
=Sowing.= The best time for sowing beetroot is the beginning or middle of
April. If sown too early, the young plants may be partially injured by
frost; if later than the first week in May, the crop may require to be
taken up in autumn, before it has had time to get ripe. About 10 to 12
lbs. of seed is required per acre. As regards the width between the
plants, generally speaking, the distance between the rows and from plant
to plant should not be less than 12 nor greater than 18 in. Should the
young plants be caught by a night's frost, and suffer ever so little, it
is best to plough them up at once and re-sow, for they are certain to run
to seed, and are then practically useless for the manufacture of sugar.
Sugar-beets require to be frequently horse- and hand-hoed. As long as the
young plants are not injured, the application of the hoe from time to
time is attended with great benefit to the crop. It is advisable to
gather up the soil round each plant, in order that the head may be
completely covered with soil. Champonnois' researches point to the
advantage of planting in ridges, by which the supply of air to the roots
is greatly facilitated.
The conditions best calculated to ensure the roots possessing the
characters most desirable from a sugar-maker's point of view are chiefly
as follows: (1) Not to sow on freshly-manured land; it is eminently
preferable not to manure for the beet crop, but to manure heavily for
wheat in the preceding year; (2) not to employ forcing manures, nor to
apply manure during growth; (3) to use seed from a variety rich in sugar;
(4) to sow early, in lines 16 in. apart, at most, the plants being 10 to
11 in. from each other; there will then be 38,000 beets on an acre,
weighing 21 to 28 ounces each, or 52,800 to 70,400 lbs. per acre; (5) to
weed the fields as soon as the plants are above ground, to thin out as
early as possible, and to weed and hoe often, till the soil is covered
with the leaves of the plants; (6) never to remove the leaves during
growth; (7) finally, not to take up the roots, if it can be avoided,
before they are ripe, the period of which will depend upon the season.
Good seed may be raised by the following means: The best roots, which
show least above ground, are taken up, replanted in good soil, and
allowed to run to seed. This seed is already good; but it may be further
improved by sowing it in a well-prepared plot possessing all the most
favorable conditions; the resulting plants are sorted, set out in autumn,
put into a cellar, and in the spring, before transplanting, those of the
greatest density, and which will give seeds of the best quality, are
separated. These are transplanted at 20 in. between the rows and 13 in.
between the feet, which are covered with about 1-1/2 in. of earth.
Finally they are watered with water containing molasses and
superphosphate of lime, as recommended by Corenwinder.
=Harvesting.= Sugar-beets must be taken up before frost sets in. When the
leaves begin to turn yellow and flabby, they have arrived at maturity,
and the crop should be watched, that it may not get over-ripe. If the
autumn is cold and dry, the crop may be safely left in the ground for
seven to ten days longer than is needful, but should the autumn be mild
and wet, if the roots are left in the soil, they are apt to throw up
fresh leaves, and nothing does so much injury. In watching the ripening
of the crop, a good plan is to test the sp. gr. of the expressed juice. A
root or two may be taken up at intervals, and reduced to pulp on an
ordinary hand-grater, the juice obtained by pressing the pulp through
calico, and the density observed by a hydrometer. As long as the gravity
of the juice continues to increase, the crop should be left in the land.
Good sugar-yielding juice has a sp. gr. of about 1.065, rising to about
1.070. Immature roots, cut across, rapidly change color on the exposed
surface, turning red, then brown, and finally almost black. If newly-cut
slices turn color on exposure, the ripening is not complete; but if they
remain some time unaltered, or turn only slightly reddish, they are
sufficiently ripe to be taken up. The crop should be harvested in fine,
dry weather. In order that the roots may part with as much moisture as
possible, they are left exposed to the air on the ground before being
stacked, but not for longer than a few days, and they need to be guarded
against direct sunlight. Perhaps the best plan is to cover them loosely
with their tops in the field for a couple of days, then trim them, and at
once stack them.
=Storing.= For storing roots, especial care should be taken to prevent
their germinating and throwing out fresh tops, which is best done by
selecting a dry place for the storage ground. They may be piled in
pyramidal stacks, about six feet broad at base, and seven feet high. At
first, the stacks should be thinly covered with earth, that the moisture
may readily evaporate; subsequently, when frosty weather sets in, another
layer of earth, not exceeding one foot in thickness, may be added. This
is essentially the method generally adopted for storing potatoes and
beets.
[Illustration: FIG. 46.--Stack for Storing Beets.]
In continental Europe and Canada, extra precaution is necessitated by the
rigorous climate. In S. Russia, the plan shown in Fig. 46 is sometimes
used. The beets are disposed completely below the surface of the soil, in
a trench dug with sharply sloping sides. At about 15 in. from the bottom,
is an openwork floor of reeds, on which the beets are piled to within a
few inches of the level of the exterior soil. On the top, and following
the apex of the heap, is laid a triangular ridge-piece _a_, for the
purpose of facilitating evaporation. The whole is covered with a layer
_b_ of straw and fine earth, the thickness of which is varied according
to the indications of the thermometer _c_ placed in the center of the
mass. Between the floor of the trench and the openwork floor is a space
_d_, communicating with two vertical channels leading to the outer air,
thus providing ventilation. The outlets of the channels can be opened and
closed at will. The Russians also often employ regular cellars, as shown
in Fig. 47. The structure consists of two stories, covered with a bed of
earth, each furnished with a floor of hurdles or open planking, on which
the beets are piled to the depth of about one yard. Lateral passages
facilitate ventilation, and openings in the roof permit the heated air to
escape. The cost of erecting these cellars is heavy, but there is great
saving of labor in storing the beets, as it suffices to simply pile them
up on the floors. Moreover, the arrangement permits the examination of
the contents beyond the indications of a thermometer; and enables any
portion to be removed, even during snowy weather.
[Illustration: FIG. 47.--Storage Cellar for Beets.]
=Alcohol from Beets.= Beets contain 85 per cent. of water, and about 10
per cent. of cane sugar, the remainder being woody fibre and albumen;
cane sugar not being in itself fermentible,--as is grape sugar,--it has
to be converted into "inverted sugar" by a ferment as yeast. Either the
sugar beets may be mashed or the molasses which remains from the
manufacture of beet sugar (as described in Chapter X). The conversion of
the sugar into alcohol is effected in several different ways, of which
the following are the principal:
By rasping the roots and submitting them to pressure, and fermenting the
expressed juice.
By maceration with water and heat.
By direct distillation of the roots.
The first two methods are the best as by them the woody fibre of the
plant which is non-fermentible is separated from the fermentible juice.
In both the first and second processes the beets must first be entirely
cleaned of adhering dirt, trash and clods of earth, and then rasped,
pulped or sliced by certain machinery.
=Cleaning.= Care must be taken in this operation that the beets shall be
freed from small stones and adhering hard lumps of earth which would
otherwise get into the rasping machinery to the damage and stoppage of
the mechanism.
There are many forms of cleaners but all are alike in this,--that the
beets shall be subjected to the action of water while traveling through
or over a perforated casing. The simplest machine, and one easily
constructed by any carpenter, comprises an elongated cylinder formed of
lathes or strips spaced apart such distance as will allow dirt and stones
to pass between them. This is mounted on a central shaft and revolves in
a tank of water. It should be slightly inclined so that the potatoes or
beets to be washed may feed downward from the open upper end-disk or
wheel, to the lower end where they are thrown out. At the upper end is a
hopper and at the lower, the end disk has inwardly projecting lips, which
as the cylinder revolves lifts the beets up and tumbles them out on to an
incline which carries them to the rasping machine.
Another form of machine comprises a perforated cylinder of sheet iron,
revolving in a tank of water. A better form of cleaner than either of
those consists of an inclined trough in which a spiral feeding screw of
sheet iron rotates. The beets are fed into the trough at its lower end
and are carried upward, slowly, by the feeding screw. Above the trough is
a water pipe having a number of outlets by which water may fall on to the
beets and into the trough. The water rushing down the inclined trough
carries with it all dirt and stones, and by the time the beets have
reached the upper end they are entirely cleaned and ready for slicing or
rasping.
For pressing out the juice, the beets are mashed into a pulp, while for
diffusion the beets are sliced.
=Rasping.= Fig. 48 shows one form of rasping machine. On a suitable
supporting frame is mounted a cylinder _a_ having a diameter of about 24
inches. The cylinder is formed of alternate saw blades and wooden washers
holding them a slight distance apart. The saws or teeth are so set on the
cylinder as not to slice the beets but to shred them up into a fine pulp.
The cylinder rotates at a speed of 800 to 1000 revolutions a minute in
front of an inclined table, having a jigger whereby the beets are fed
downward against the toothed cylinder. The teeth carry the pulp downward
and it falls into a receptacle beneath.
[Illustration: FIG. 48.--Beet and Potato Rasp.]
It is best to add to this pulp a small portion of sulphuric acid, say
two-tenths of one per cent. This prevents by-fermentations.
=Pressing.= The pulp obtained from the raspers has now to be expressed.
This is either done by platen presses or by roller presses. With platen
presses the first pressing may be done by screws, but the final pressing
should be accomplished by hydraulic presses.
For the hydraulic press, the pulp is placed in woolen sacks, containing
10 to 12 lbs., superposed in the press with their mouths doubled under,
and separated by iron plates; about 25 are collected, and the pile is put
into a screw-press, called a "preparatory" press, which extracts about 45
to 50 per cent. of the juice. These pressed sacks are piled anew on the
movable plate of a powerful hydraulic press, which takes 50 at a charge.
Each preparatory press can supply four hydraulic presses, which are
ranged around it, so that of the four presses, there will be one
charging, one commencing to press, one in full pressure, and one
discharging, at the same moment. Motion is communicated to the four
hydraulic presses by four pumps mounted on the same bed, and tended by
the same workman who directs the pressing. An improvement upon the
general form of hydraulic press is that devised by La
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