The Boy's Book of Industrial Information
by Elisha Noyce · English · Gutenberg #49489 · 448,540 chars · public domain (US)
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Title: The Boy's Book of Industrial Information
Author: Elisha Noyce
Release date: July 19, 2015 [eBook #49489]
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Language: English
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*** START OF THE PROJECT GUTENBERG EBOOK THE BOY'S BOOK OF INDUSTRIAL INFORMATION ***
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NEARLY READY,
Cloth Gilt, PRICE FIVE SHILLINGS, Elaborately and Profusely
Illustrated by THE BROTHERS DALZIEL, uniform with the
BOY’S BOOK OF INDUSTRIAL INFORMATION.
OUTLINES OF CREATION. By ELISHA NOYCE.
The object of the Author is to give a simple, clear, and lucid
description of the Universe under the following divisions:--
The Sky. The Earth. The Vegetable Kingdom.
The Air. The Waters. The Animal Kingdom.
London: WARD & LOCK, 158, Fleet Street.
Illustration: (‡ Composite of several Industrial Scenes.)
Illustration: (‡ Illustrated Title Page.)
THE BOY’S BOOK
OF
INDUSTRIAL INFORMATION.
BY
ELISHA NOYCE.
ILLUSTRATED
WITH THREE HUNDRED AND SIXTY-FIVE ENGRAVINGS,
BY
THE BROTHERS DALZIEL.
LONDON:
WARD & LOCK, 158, FLEET STREET.
1858.
PREFACE.
In putting this work before the public, the Author has endeavoured
to supply a clear and brief description of the materials, processes,
and apparatus made use of in the various examples of industry and
skill constantly before our eyes, so that the reader may acquire a
knowledge of such things, and an interest in those, who, by their
hard work and patient ingenuity, supply them; for every article and
process can be made to have a value and an interest, in proportion to
the amount of knowledge we possess respecting them.
* * * * *
There is no attempt in this work to describe every article and
process, but such only as are most interesting and instructive. All
the mere trades and handicrafts--the results of which are so various,
and depend so completely upon the skill of the artisan, that any
description of their particulars would scarcely be profitable or
interesting to the reader--have been avoided. The illustrations of
this work have been prepared with the greatest care, and drawn from
reality. By the kind permission of Lord Panmure, the artists were
allowed to make whatever drawings were necessary in the Arsenal at
Woolwich; and thanks are due to many of our eminent manufacturers for
similar favours with respect to their several factories and machinery.
* * * * *
In the first division of this work have been placed all those
materials which exist in nature, either isolated or combined, and
which have merely to be extracted or separated, as the earths,
metals, &c. Under the second division, “Manufactured Products,”
such results of manufacture as are known by the common designation
“stuff,” and are of an uniform and particular quality, as soap,
soda, &c., not existing in Nature as such. In the third division,
individual articles, the result of skilled labour, each compounded
and made up of several substances, or of particular forms. In the
fourth section are the processes made use of in the production of
the various necessaries or elegancies of life. Some of these might
have been placed under the second and third divisions, but the Author
thought proper to place them here, on account of the processes being
more readily described than their results. The fifth division is
devoted to the most usual forms of Apparatus and Machinery of general
application, avoiding all mere tools and machines for specific
purposes. The last division is a mere outline of those important
engineering works which of late have acquired an increased interest
from the addition of railways and electric telegraphs to their number.
INTRODUCTION.
The inquiring mind uses all its senses to obtain some new idea, and
to apply it to some useful purpose; it is this spirit of research
that has led to all the great results in Art and in the mechanical
and chemical sciences, which we now enjoy and admire; but it is only
by very slow degrees, and by great perseverance, that such results
are obtained, although the accumulation of a few years makes an
enormous aggregate. Look back a generation or two--where was then
the steam engine, where the tall stalks which indicate the sites of
complicated and ingenious manufactures? the blacksmith then worked
at his anvil, and wrought out with his hands what he required in
iron; but what is now done with this treasure of the mine? behold
the Leviathan and the Britannia Bridge,--count their thousands of
tons of plate iron rolled out by machinery, and think of the work
of their removal, the millions of rivets to fix them together, the
elevation of the one, and the launching of the other. Could this be
done without that machinery which has become gradually perfected by
thought and perseverance? Visit the iron works and see the powerful
“steam hammer” moulding into form a mass of red-hot iron, many tons
in weight; see the powerful and beautiful contrivances for rolling
into plates, drawing into bars and wire, or cutting up this stubborn
metal, and call it stubborn no more! See the powerful “locomotive”
carrying along the trams hundreds of tons of goods at a rate that
can hardly be equalled by the bird that flies through the air on
its light pinions; and the huge steam ships which cut their rapid
way across the seas, holding in contempt those very winds upon
which alone the mariner used to depend! See with what rapidity and
accuracy almost every kind of “textile” material is produced by the
steam-worked loom, and remember that these have all arisen, with
hundreds more, from small beginnings, and step by step.
Nor does the mechanical genius bound the works of civilisation.
From studying the various properties of the elements of nature, and
the results of their combination in various proportions and under
various conditions, the chemist arrives, not only at their uses
and applications, but obtains results before quite unthought of!
Instance the electric telegraph, and think how it conveys one’s
thoughts half round the globe before you can express an exclamation
of surprise that such things can be! See also the wonderful results
of the photographic art, copying the most elaborate picture,
machine, or portrait, in a few seconds, and see the results of
electro-deposition, which by an invisible agent, coats with pure
gold or silver any article subjected to its action, or produces in a
mould the article itself of the most elaborate form or pattern, and
in solid metal, extracted by this all-powerful agent from liquids
which the uninformed would never believe could contain any metal at
all. Think of the beautiful colours of our carpets, draperies, silks,
&c.--the chemist has devised the dyes with which they are stained;
and in our chemical factories, what tons of vitriol, soda, bleaching
powder, and scores of other chemical agents are daily produced. All
this is the result of study and perseverance. Neither have the Fine
Arts been behind in contributing to civilisation, as may be seen in
the structure and decoration of our houses, churches, and public
buildings; in our glass and pottery ware; paper hangings, and other
artistic designs; in engraving and the copious illustration of our
books, saving a long and tedious description, and often presenting to
the eye forms that words could not express. And now let us consider
one by one the “materials” and processes from which all these results
arise.
CONTENTS.
NATURAL PRODUCTS:
Earths
Metals and Alloys
Iron
Copper
Lead
Tin
Zinc
Mercury
Gold
Silver
Platinum
Nickel
Coal
Sulphur
Plaster of Paris
Salt
Stone
Wood
Cotton
Flax
Silk
India-rubber
Gutta-percha
Wax
Nitre
Blacklead
Spermaceti
MANUFACTURED PRODUCTS:
Sugar
Alcohol, or Spirit
Starch
Soap
Stearine
Soda
Wines
Vinegar
Coal Gas
Tar
Acetic Acid, or Wood Vinegar
Varnishes
Oils
Inks
Charcoal
Cements
Coke
Gunpowder
Gun-cotton
Phosphorus
White Lead
Prussian Blue
Prussiate of Potash
Sulphate of Iron
Sulphate of Copper
Chloride of Lime
Sulphuric Acid
Leather
Glue and Size
Parchment
Catgut
Paper
Malt
Chocolate and Cocoa
Steel
Tin-plate, and Galvanised Iron
Glass
Soda-Water
Coal-tar Naptha
Wood Naptha, or Pyroxylic Spirit
PRODUCTS OF SKILLED LABOUR:
Pottery
Bricks and Tiles
Tobacco-pipes
Gold-Leaf
Shot
Files
Type
Lucifer-matches
Candles
Rope
Wire
Cutlery
Nails
Screws
Pins
Needles
Tubing
Steel-pens
ARTS AND TRADE PROCESSES:
Wood and Plate Engraving
Lithography
Printing
Photography
Bookbinding
Paper-staining
Flax Manufacture
Glass-painting
Cotton Manufacture
Woollen Manufacture
Weaving
Bleaching
Calico Printing
Dyeing
Calendering
Bread-making
Sugar Refining
Brewing
Distillation
Gilding
Silvering Looking Glasses
Silver Plating
Electro-plating and Deposition of Metals
Soldering and Brazing
The Smelting of Metals
Founding
Glass-blowing and Casting
Glass Cutting
Bricklaying
Stone-cutting
APPARATUS AND MACHINERY:
Steam Engines
Boilers
Furnaces
Bellows and Blowing Machines
Screw Propellers
Anchors
Chains
Cranes
Cranks
Fire-arms and Projectiles
Percussion Caps
Pumps and Fire Engines
Valves
Wheels
Watermills
Windmills
Syphons
Stopcocks or Taps
Filters
Presses
Stills
Blowpipes
Thermometers
Barometers
Pendulums
Ploughs
Harrows
Rollers
Mowing Machines
Thrashing Machines
Reaping Machines
Drills
ENGINEERING WORKS:
Railways
Electric Telegraphs
Roads
Bridges
Tunnels
Drains
Artesian Wells
Mines
Ships
Canals and Locks
NATURAL PRODUCTS.
EARTHS.
Illustration: (‡ Illustrations of:)
1. EMERALD. 3. FORTIFICATION AGATE. 5. DIAMOND.
2. GARNET. 4. RUBY. 6. ROCK CRYSTAL.
All earths are metals in combination with oxygen: that is to say,
they can all be separated into a metal and oxygen. The chief earths
used are Alumina, found as clay or slate; Lime, found as chalk or
limestone; and Silica, found as sand, flint, or rock-crystal. These,
in various proportions, combined with some few other matters, form,
by far, the greatest portion of the earth we dwell on. The earths,
when pure, are all white substances, not very heavy, and having
scarcely any of the properties of the metals from which they are
derived. The next frequent of the earths are Baryta and Strontia;
but these may be said to be useless when compared with the three
former. Alumina, in its various forms of clay, is used for brick and
tile-making, and for pottery; hardened into the form of slate, it is
much used for roofing and for making cisterns. Lime, in the form of
carbonate, constitutes the best building stones, including marble,
so valuable for ornamental carving and decoration, and when burnt,
to separate the carbonic acid, forms lime itself, which is invaluable
as a cement when mixed with sand; lime, in union with another acid
(sulphuric) forms plaster of Paris, also a most useful article
in the arts, &c. Silica, in the form of sand, is very extensively
used for glass making, and, in the form of flint, it is ground and
used for pottery: all such stones as quartz, rock-crystal, Scotch
pebble, agate, cornelian, &c. are but various forms of Silica, either
crystallized or deposited in layers. Most of the precious stones
are composed of the earths in a crystalline state and colored by
some foreign ingredient, such are the emerald, ruby, garnet, &c.
The diamond is not an earth but composed of pure carbon.
METALS AND ALLOYS.
Metals may be known from all other substances by certain properties:
they have that peculiar brilliancy, called, for that reason, the
“metallic” lustre; they are rapidly heated, and as rapidly cool,
hence they are said to be good conductors of heat; they are all
opaque, and most of them very heavy; some indeed, as gold and
platinum, are the heaviest substances known, being about twenty times
heavier than water; they have, moreover, other valuable properties
such as the capability of being melted, of being drawn out into wire,
of being beaten into thin plates, &c.
All metals are simple bodies; that is to say, they cannot be made
out of other substances, although two or more metals may be combined
and be again separated, or they may be combined with numerous other
substances, as oxygen, and also again separated. There are upwards
of fifty metals known to chemists, yet but few are used to any extent
in the arts or manufactures. All the metals in use for the very many
purposes to which they are applied are not simple metals, but are
what are called “alloys,” that is to say, compounds of two or more
metals. The chief metals in use are--
IRON, MERCURY,
COPPER, NICKEL,
LEAD, GOLD,
TIN, SILVER,
ZINC, PLATINUM.
But in the state of oxide many are used which are seldom seen in the
metallic state, such are the earths and alkalies; and for colors, and
several other purposes, many other preparations are in use. The chief
alloys, or compound metals in use, are, brass, made of copper and
zinc; pewter, made of lead and tin; bell metal and gun metal, made
of copper and tin; and solder, which is a kind of pewter, and made of
the same metals; the silvering for looking-glasses is made of mercury
and tin; the gold and silver used for coin are not pure metals, but
alloyed with two parts of silver or copper to every twenty-two of the
pure metal, and this forms the “standard” gold or silver. The gold
used by jewellers has often a much greater proportion of alloy--for
this name is given both to a compound metal and the cheaper metal
made to combine with the more precious. The object gained by thus
alloying the coinage, is that of rendering the metals harder, so that
they shall not suffer much loss in wearing; thus a small quantity
of copper mixed with either gold or silver, renders them both harder,
although itself softer than either. The combination of certain metals
forming alloys, is often not exactly the mean of their respective
qualities, for instance, a small quantity of silver is sometimes
fused with cast steel for penknife blades, and although the silver is
itself much softer than the steel, yet the combination is found to be
both closer in the grain and harder; it is known as silver-steel in
commerce. Bismuth, although itself not very fusible, increases the
fusibility of other metals; a combination of 2 parts tin, 3 lead, and
5 bismuth, forms a metal fusible by boiling water.
IRON.
Illustration: NATIVE OXIDE OF IRON.
Iron stands first in usefulness of all the metals, for railways,
bridges, ships, and a thousand other purposes; it can be both cast
and wrought, having that peculiar property, the capability of being
“welded,” that is to say, of softening while hot to such an extent
that when two pieces are made white hot and laid together, a few
blows of the hammer will cause them to unite into one piece, and it
is by means of this most useful quality that large masses of wrought
iron are produced, such, for instance, as anchors and cranks for
steam-boats. This property of welding, and the abundance of the ores
of iron, render it one of the most useful materials supplied by
nature for the various purposes of manufacture. In combination with
carbon it forms that hardly less useful article known by the name of
steel.
Cast Iron has scarcely any of the metallic lustre, and is only fitted
for solid work; it is brittle, like steel, without its elasticity,
and is too soft and too porous to be made into any of the numerous
tools and instruments for which steel is so eminently suitable.
Cast iron contains many impurities, the chief of which are carbon,
sulphur, and silica, got from the coke whilst being smelted in
contact with it, and from the fluxes used in the process; it is
coarse in grain, and much more fusible than wrought iron, which
is iron in a nearly pure state and can be fused only by the very
highest heat capable of being produced. Cast iron is converted into
wrought or malleable iron by being re-melted and stirred for a long
time in contact with the air, this process is called “puddling,”
its object is to get rid of all the impurities (chiefly carbon and
sulphur) which, by being brought into contact with the air at a high
temperature, are said to be burnt out, that is to say, they combine
with oxygen and form carbonic and sulphurous acids. After puddling,
the iron is rolled or hammered out, folded up, and again extended,
and as a general rule it may be said, the more this is continued the
purer and softer is the iron.
COPPER.
Illustration: NATIVE COPPER.
Copper is a reddish-coloured heavy metal, much used for sheathing
the under part of ships, for making boilers, &c. It is about
eight-and-a-half times heavier than water, and is too valuable to be
used for many purposes where either iron, tinned iron, or zinc are
applied, but for which purposes its great durability would fit it,
as it is easily rolled out or beaten into plates, and is not quickly
acted on by the weather. It is used as coin in pence, halfpence, and
farthings; all vessels for cooking purposes, when made of copper, are
tinned inside to prevent the food becoming poisonous from verdigris,
which is the rust of copper, and is very injurious. Copper is found
chiefly combined with sulphur, forming “native sulphuret of copper.”
Copper melts at a full red heat.
LEAD.
Illustration: SULPHURET OF LEAD.
Lead is a heavy metal, of a dull blueish tint, and very soft; it is
extensively used for covering roofs, for cisterns, and for pipes for
conveying water, as it is easily bent and joined, and is not acted
on by the water which passes through it. Lead melts at a heat below
that of redness, and, in combination with oxygen and carbonic acid,
forms the “white lead” of commerce so largely used as a paint. Oxide
of lead, called “litharge,” enters into the composition of flint
glass, and in combination with a larger quantity of oxygen forms “red
lead,” a substance much used in painting. Lead is found in many parts
of England, especially Cornwall, where many lead mines exist; it is
got from the sulphuret called “galena,” which is lead in union with
sulphur. What is called “black-lead” is not lead at all, but is an
ore of iron, being iron in combination with carbon. Lead is about
eleven-and-a-half times heavier than water.
TIN.
Illustration: OXIDE OF TIN.
Tin is a white metal, almost as white as silver, it is found chiefly
in Cornwall. It is a light, soft metal, and, like lead, is easily
melted; it is used chiefly for coating vessels of harder metal, such
as iron and copper. It is used to mix with copper to produce bronze,
bell metal, and gun metal, and with lead to produce pewter, which
used to be so extensively used as table-ware before the manufacture
of earthenware became general for that purpose. Tin does not easily
tarnish or rust by exposure to the air, hence the use of tinned
iron-plate. Tin, united with mercury, forms the silvering for
looking-glasses. Tin is about seven-and-a-half times heavier than
water.
ZINC.
Illustration: SULPHURET OF ZINC.
Until the last quarter of a century, zinc was but little used, but
of late it has taken the place for many useful purposes where lead
was formerly used, principally owing to its cheapness and lightness.
Zinc is a hard metal of a grayish colour, not easily bent but rather
brittle, but when made nearly red hot, it is capable both of being
rolled out into sheets and being beaten into form by the hammer. Zinc
is about six-and-three-quarter times heavier than water. Like many
other metals, zinc is volatile, that is to say, when heated to a
certain extent it passes off into vapour, and there is no doubt, the
reason that zinc was not known or used of old was that it was chiefly
lost in “smelting,” or getting it from its ores. Zinc is now obtained
by a sort of distillation; the ores are mixed with the flux, &c.,
in a large earthen crucible or pot, from which an iron tube passes
into a vessel of water, the lid is securely fastened on, and as the
heat is urged the zinc is driven off in vapour, passes down the tube
and condenses in the water. The zinc of commerce is obtained chiefly
from the ore known by the name of “calamine stone,” which is zinc in
combination with oxygen and carbonic acid. A substance called “zinc
white” has been lately introduced as a substitute for white lead, and
would certainly supersede it, but the zinc is found to be deficient
in “body,” which means, the power of covering anything over which
it is laid-on in a thin layer, but as zinc white does not blacken
in foul air, and white lead does, it has a great advantage, and it
is to be hoped that some improvement in its manufacture may improve
its “body.” Zinc is chiefly used for roofs, gutters, water-pipes,
cisterns, and various vessels for holding water, as it does not rust
so easily as iron. What is called “galvanised iron,” is iron dipped
into melted Zinc in the same way that tin-plate is.
MERCURY.
Mercury, or quicksilver, is known from all other metals by being
fluid at the ordinary temperature of the air. This is only owing to
its extreme fusibility, for at 72 degrees below the freezing point
of water, it also becomes solid, and may be hammered out or cut by a
knife; it is very heavy, being about fifteen-and-a-half times that of
water, so that most of the metals will float on its surface; it has
a bright lustre and is almost as white as silver. It is found both in
the fluid metallic state, and in combination with sulphur, in which
last state it is called “cinnabar;” this is a heavy mass of a deep
red color, and when ground to powder, of a most magnificent red,
and is the vermillion so well known as a pigment; this vermillion is,
however, most frequently manufactured by combining the mercury and
sulphur, both first purified, in this way a more brilliant color is
produced than can be got from the cinnabar. The metal is extracted by
heating the cinnabar with iron-filings or lime in a retort, by which
means the mercury distils over and the sulphur is left behind united
with the iron or lime.
Mercury is used for many purposes in the arts and sciences, for
barometers, thermometers, compensating pendulums for clocks, &c., and
also in the processes of water-gilding, looking glass silvering, and
in the Daguerreotype process. The combinations of mercury with other
metals are called “amalgams.”
GOLD.
Illustration: GOLD (‡ NUGGET).
Gold is the heaviest of the metals with the exception of Platinum,
being rather more than nineteen times heavier than water; it is of
a bright yellow color, and is not tarnished by exposure to the air
or moisture, hence its usefulness in ornamenting frames, cornices,
&c. Gold is chiefly used, in the form of coin, as the medium of
exchange; for ornamental purposes, such as jewellery; for gilding,
and for staining glass, to which it gives a beautiful ruby-red color.
Gold coin contains about one twelfth part, by weight, of copper,
this is added to give it hardness and consequently cause it to lose
less by wear in use. Gold is not dissolved by any of the pure acids,
but a mixture of hydrochloric and nitric acids will dissolve it in
consequence of giving out chlorine, an element which freely dissolves
gold.
Gold is capable of being beaten out into leaves of extreme thinness,
and also of being drawn into wire of such thinness that five hundred
feet of it weigh but one grain.
SILVER.
Illustration: SILVER.
Silver is the whitest of the metals; it is about ten-and-a-half
times heavier than water; it does not easily tarnish by the air,
and is not converted into dross by heat continued for any length of
time, or, in chemical language, it is not oxydised; it is chiefly
used for coin and for ornamental purposes where its cleanliness and
beauty are strong qualities to recommend it. Many kinds of lead ore
contain silver, and when this is in sufficiently large proportion to
pay for its extraction, the reduced lead is subjected to the flame
of a furnace which is blown on to it with a strong blast, the flame
melts the lead and converts it into an oxide called “litharge,”
which is in the form of reddish scales, and as these are formed the
blast blows them off; in this way the lead is gradually consumed,
leaving the silver with but a small quantity of lead, this is put on
to a cup made of bone ashes called a “cupel,” hence this operation
is called “cupellation,” the heat is then raised, and the lead
which remains with the silver, forming a liquid glass with the bone
ashes, sinks into them, leaving the silver bright and pure. Silver
in some districts is extracted from its ores by what is called
“amalgamation;” the finely powdered ore is mixed with water, some
cuttings of iron and quicksilver, and turned round in a barrel for a
considerable time, when the quicksilver is drawn off through a small
hole, and is found to contain all the silver in the ore, together
with some other metals. The quicksilver is got rid of, first by
pressing and then by distillation; so that it is all recovered for
a second operation. What remains is separated from the other metals,
which it may have been mixed with by different processes, according
to the nature of these metals.
The standard silver of the Mint is what is called 22 carats fine
(nearly), that is to say, 22 parts in 24, the two parts being copper;
this is done to harden it. The silvering of looking-glasses is made
of a compound of tin and mercury, but a process for really silvering
looking-glasses has been patented by Mr. Drayton; it consists of
precipitating silver from its solution by means of the oil of Cassia,
or some other volatile oil: the process is far too expensive for
general use or for large plates. Silver leaf is made and used in the
same way that gold leaf is.
PLATINUM.
Platinum is a metal of a white color, and is the heaviest substance
known, being more than twenty-one times heavier than water. It is
capable of being welded and wrought out by the hammer like iron; it
is not acted on by any of the acids, but, like Gold, is dissolved
by chlorine or a mixture of hydrochloric and nitric acid; it does
not tarnish by exposure to air, and is extremely difficult to melt,
requiring the very highest heat that can be produced; these qualities
render it one of the most useful of the metals to the chemist,
furnishing him with retorts, crucibles, and evaporating dishes
suitable for many purposes; its high price, however, renders it not
so generally used as it would otherwise be.
NICKEL.
This metal is of a white color and very difficult to melt, it is
about eight times heavier than water and is chiefly obtained from the
ore known as kupfer-nickel, found very plentifully in Germany; this
kupfer-nickel is a native arseniuret of nickel, that is, nickel in
chemical combination with arsenic. It is very difficult to separate
these two metals, but an effectual and cheap process has lately been
devised to do so.
Nickel is attracted by the magnet similar to iron but in an inferior
degree. Till lately nickel was but little used, but it now forms the
basis of those compound metals known as nickel-silver, German-silver,
and British-plate, all which varieties are generally employed as
an economical substitute for silver; it is also used largely as a
foundation on which to deposit pure silver by the electro-plating
process, for which purpose it is most admirably suited being very
superior to copper in consequence of its color, as the silver always
wears off unequally and exposes the ground work of metal beneath.
German-silver is composed of copper, nickel, and zinc, in various
proportions. Nickel always forms one of the constituents of meteoric
iron, those mysterious masses called aerolites, which sometimes fall
to the earth.
COAL.
Illustration: MINERALS (‡ INDUSTRIAL SCENE).
This, the richest product of the mine, the well-known fuel used in
almost every branch of industry as well as for warming our houses,
is got from the depths of the earth, where it exists in certain
localities forming what are called “coal fields” or “basins.” It is
the result of changes produced during many ages upon vegetable matter
buried during the various convulsions which the earth has undergone,
and pressed into layers or strata of various thicknesses. To raise
this valuable fuel, powerful machinery is used and deep shafts are
sunk at an enormous expense.
Coal exists in various forms: the following are the most easily
recognised:--
1.--Cubical coal; shining and easily broken into squarish fragments.
It burns brightly.
2.--Slate coal; dull in color, splits like slate. Burns well.
3.--Cannel coal; dull color, breaks like resin, and somewhat
resembles jet. Burns brilliantly, and splits with a crackling noise
when in the fire. It affords the best gas.
4.--Glance, or Kilkenny coal; steel-grey color and metallic lustre.
Burns without flame or smoke, somewhat like charcoal.
5.--Lignite, or brown coal; is an imperfectly formed coal.
The quantity of coal used is rapidly increasing owing to the
extensive number of steam engines used, especially for navigation
and railway transit; and it is a problem, not yet determined, how
long the coal existing in Great Britain is likely to last; the lowest
statements make it but little below a thousand years.
SULPHUR.
Sulphur, also called Brimstone, is a natural production, and is
found either pure, or combined with metals forming ores, for the
most part called “pyrites,” as, iron pyrites, copper pyrites, &c.
In chemical language these compounds are called “sulphurets” or
“sulphides.” Sulphur is one of the elements; that is to say, it is
a simple body, or one neither capable of being made nor separated
into other ingredients. It is crystalline, of a bright yellow color,
very inflammable and volatile, burns with a blue flame and gives off
pungent fumes of sulphurous acid. It is got pure by distillation from
various substances containing it, and in Sicily is found nearly pure
as a volcanic product. Sulphur is chiefly used for the manufacture of
sulphuric acid and gunpowder, and was also largely used for making
matches, but phosphorus (a still more inflammable substance) has
almost superseded it in the manufacture of this necessary article.
PLASTER OF PARIS, OR GYPSUM.
Plaster of Paris is sulphate of lime--a combination of lime and
sulphuric acid; and exists abundantly in various degrees of purity;
it occurs plentifully in the locality of Paris, and is brought here
in masses of a greenish, pink, or brown color. To prepare the gypsum
it is first made red hot, to separate the water which it contains,
and then ground to powder of various degrees of fineness. Plaster of
Paris has the peculiar property of uniting with a certain quantity
of water and forming a solid compound with it; upon this property
all its usefulness depends. If a portion of Plaster of Paris be
mixed with sufficient water to form a liquid of the consistence of
cream, in a few minutes it will harden and become quite set, and
as it dries, it will harden still more, till it is of a hardness
almost equal to stone: this useful property causes it to be much used
for casting figures and ornaments; cheap plaster figures, &c., are
generally cast hollow, to save the plaster; this is done by pouring
into the mould a certain quantity of the plaster mixed with water,
and quickly turning the mould about so that it shall adhere and form
a layer on all the inside of the mould; when set hard, the mould is
taken to pieces and the figure finished by scraping off the marks
where the mould was joined. Plaster of Paris, combined with whiting,
forms what is called by plasterers “putty,” and is much used for
ceilings, and similar purposes.
SALT.
Salt is one of the most widely spread and plentiful minerals which
the earth gives for the use of man; all the water of the ocean
derives its saline taste from salt; many springs are completely
saturated and are hence called “brine springs,” and it also exists
crystallized in beds within the earth of immense thickness and
extending for miles each way. The salt mines of Cheshire are the
finest and most extensive in England, and in some places the stratum
or layer of salt is more than one hundred feet thick, perfectly white
and crystallized. Salt is not a simple body, but is composed of two
simple bodies or elements, chlorine and sodium, hence it is called
by chemists the chloride of sodium, it can be formed by putting
carbonate of soda into hydro-chloric acid (sometimes called muriatic
acid,) until no more effervescence takes place, the result will taste
salt and yield pure salt on evaporation. The waters of the sea are
in some places evaporated by the heat of the sun in shallow hollows
dug out in the beach, this is called “bay salt” and is very impure;
but the chief part of the salt of commerce is procured by evaporating
the waters of brine springs; this water is pumped up into large iron
cisterns placed beneath slight sheds to keep the rain off, and having
flues running beneath them, the first impurities are thrown away,
and as evaporation goes on, the salt crystallizes and falls to the
bottom of the cistern in a fine white powder; this is taken out with
wooden shovels and placed in conical vessels with a hole in their
lower part to drain off all the moisture; it is then dried by stoves
and is fit for use; when no more salt falls down, the impure liquor,
called “bittern,” is drawn off and used to procure Epsom salts from,
by mixing it with sulphuric acid. The bittern contains chloride
of magnesium, and the sulphuric acid changes it into sulphate
of magnesia, which, when purified, forms the Epsom salts sold by
druggists.
About half a million tons of salt are made in England every year.
Salt, besides its general use as a condiment, and in preserving
food for storing ships, &c., is also used for several manufacturing
purposes. By adding sulphuric acid and heating it, the acid called
“hydrochloric” is given off, which is largely used for many purposes;
but the chief use made of salt by the manufacturing chemist is to
prepare soda for cleansing and soap making.
STONE.
Illustration: STONE QUARRY.
Stone for building is chiefly of four kinds:--lime-stone, sand-stone,
granite, and marble. Slate is never used for building, but is very
suitable for roofing. The most common stone is limestone, and that
brought from Portland Island is especially good for building-stone;
it is called Portland stone, and it is of this stone that St. Paul’s
Cathedral is built, and most of the other public buildings of London:
it is rather soft when first dug from the quarry, but hardens with
age. Sandstone is a very coarse kind of stone, and is only used
where not much exposed to the weather; it consists of grains of
sand adhering so firmly together as to form a stone of considerable
hardness. Granite is a very hard stone, and very durable; so hard
that it cannot well be carved, and is therefore only used where
durability and plain solidity are required; London Bridge and the
Euston Square Terminus of the Birmingham Railway are built of
granite. Marble is a very fine heavy kind of limestone, sometimes
quite white, and generally partly transparent; the white kind is
very expensive, and is used for statuary, that is to say, for carving
into figures, vases, &c.; it is very durable, but is too expensive
for general use. Chimney-pieces, slabs for washing-stands, and other
articles of that description, are also made of it.
Limestone, marble, and also chalk (a soft kind of limestone), all
become changed into lime if made red hot, hence the name, limestone,
is often applied to all three.
Stone quarries are those places where stone exists of a quality
suitable for building purposes, and in a situation admitting of its
easy removal. All stone, with the exception of granite and marble,
exists in layers or strata as they are called, so that the stone
can be easily split in the direction of these strata or seams. When
a large piece of stone has to be removed, wedges are driven in a
row into these seams, and when the stone has started, it is notched
at the sides and back, so that in general a square piece is thus
removed; if it be not so, it is generally made into a somewhat square
before leaving the quarry, hence the name, derived from the French
“_quarre_.” Granite having none of the lines of cleavage, as they
are called, is broken by a row of wedges driven till a crack forms
from one to the other. Slate is a clay-stone found in layers like
limestone, but much more perfect; so much so, indeed, that it can
be split into slices a quarter of an inch thick and one or two feet
square; these, when sorted into sizes, form the slates for roofing
houses. It has been much used of late in thick slabs, cut by circular
saws, for making cisterns, a purpose for which it is well adapted.
WOOD.
Illustration: (‡ LOGGERS.)
Wood is an article of universal application; its lightness, strength,
and the facility with which it can be worked, render it almost
invaluable; although in ship-building and many of its applications
to house-building iron has to some extent superseded it, yet there
are so many other ways in which it is indispensable, that it may
be looked upon as one of the greatest boons to mankind. There is
scarcely a use to which wood may not be applied, whether as fuel
for fires, timber for building, furniture both useful and ornamental,
various parts of machinery, vessels to contain wine and other fluids,
handles to instruments, (for in cold climates and cold weather metal
cannot be handled with impunity), and indeed for all uses in which
lightness, dryness, warmth, and variety of form are desirable, wood
serves as an excellent material. The kind of trees that produce wood
fit for building and other useful purposes are those called by the
botanists _exogenous_. Amongst which the pine tribe, oak, ash, elm,
and beech, stand pre-eminent; while mahogany, walnut, and rosewood
are chiefly used for ornamental purposes; box-tree wood is also very
useful on account of its closeness and evenness of grain; it is the
wood used by engravers.
Wood when first cut is wet and heavy, but, by being exposed to the
air, it shrinks and the sap dries up in it, it is therefore liable to
swell and become damp in moist situations this is detrimental to its
usefulness; most woods therefore are improved by being soaked a long
time in water, this cleanses it from saline and extractive matters
which keeps the wood damp, but which, when separated, allow the wood
to shrink and harden permanently, this process is called seasoning,
the same effect may be produced by exposure to the air and rain,
it is generally resorted to when the timber is cut up into smaller
pieces. The structure of wood is porous, hence its lightness, it has
also a grain which runs the whole length of the wood in circles round
its centre to the surface, one of these circles is produced every
year while the tree is growing; wood is therefore capable of being
cleft in the direction of the grain by a wedge, in this way builder’s
laths are made. Wood cannot be cleft across the grain, but must be
cut by sawing or otherwise. The pine or fir tribe produce the largest
and straightest timber, but it is not so strong nor so durable as oak
and many other woods.
Some specimens of the _Araucaria Excelsa_ or Norfolk Island pine,
have stems upwards of three hundred feet high, and in the Crystal
Palace is the bark of another gigantic tree the _Wellingtonia
Gigantea_.
COTTON.
Illustration: COTTON (‡ PLANT).
Cotton consists of the fine long hairs which grow from the seeds of
several varieties of _Gossypium_, a plant belonging to the natural
order of _Malvaceæ_. These hairs are so long and numerous that they
completely fill the pod or seed vessel; they are very delicate, and
of the same size throughout, and but seldom jointed, they are each
separate from the other.
The cotton plant is chiefly cultivated in America and India. In
India, and some of the islands in the Indian Ocean, cotton has
been cultivated, spun, and woven into textures from time immemorial.
Cotton fabrics were in use in Mexico before its conquest by the
Spaniards, and have been used in China for many hundred years; its
chief source now is America, where more than two hundred times the
quantity is grown at present than was grown there half-a-century ago;
but the internal communication brought about by railways in India,
may, in all probability, revive the cultivation of cotton in that
country; the cost of conveyance from the interior having been one of
the greatest drawbacks to its exportation.
Cotton is not only cheaper than linen (which is woven from flax),
but has several advantages over it: it takes dyes much better, and
produces brighter colors; the improvements made in the machinery
for spinning and weaving cotton, have not only enabled us to match
the spinners and weavers of India, which, for a long time supplied
nearly the whole of Europe, but at the present time, cotton cloths of
English manufacture are exported to India for the purpose of clothing
the natives of that country.
FLAX.
Illustration: FLAX (‡ PLANT).
Flax is obtained from the stalks of the flax plant _Linum
Usitatissimum_, it is supposed to have been originally brought
from Egypt, where linens have been woven from its fibres from time
immemorial. It is now found growing wild in this country, and is
cultivated in most parts of Europe, either for its stalks to make
flax, or for its seed (linseed), which is used for fattening cattle,
and yields an oil (linseed oil) much used in the making of paint. The
plant grows to two or three feet in height, bears a blue flower in
July, and has a great hollow stem; when gathered, it is pulled up by
the roots. The fibres of flax are very long and even; it is the inner
part which yields the best fibres.
SILK.
Illustration: SILK (‡ WORMS).
Silk is by far the strongest of the textile fabrics, being nearly
three times as strong as flax; it consists of the filaments spun by
the silk-worm, _Phalœna Bombyx Anori_. These filaments are always
double, proceeding from two holes in the head of the worm, and are
united by a sort of varnish which is moist and clammy when the
threads proceed from the insect, and causes them to adhere together.
The silk-worm in spinning, moves the head backwards and forwards,
attaching the threads on alternate sides and all around till it is
completely covered in with a ball of silk; in this state it is called
a “coccoon.” The silk-worm, like others of its class, undergoes four
changes or metamorphoses--the Egg, the Grub or Worm, the Chrysalis,
and the Imago or perfect insect, which, in this case, is a moth. The
worm spins the coccoon to defend itself from injury and cold, but
man, taking advantage of the useful qualities possessed by these fine
filaments, spins them into his most gorgeous apparel. The coccoons
are unwound by placing them in a basin of warm water, which dissolves
the varnish, and they are then slowly wound off; formerly this was
done by hand, but now machinery is chiefly employed which winds off
the silk from a bowl full of coccoons at the same time. The silk
is coiled into hanks or skeins, and in this form is imported into
this country; from these hanks it is wound off on to large six-sided
wheels called “swifts,” and from these on to bobbins or reels; it is
then wound off from two or three of these bobbins on to one other
bobbin, the threads of silk being laid side by side, and in this
process a twist is given to it in one direction and two of these
wound on to another receiving a twist in an opposite direction, this
forms a fine cord called “organzine,” which is used by the silk
weaver in the same way that yarn is by the cotton weaver. The short
and broken pieces are carded and spun like cotton, and is called
floss silk. The raw silk is of a bright buff or golden yellow color,
but there are some kinds which are white.
INDIA-RUBBER.
India-rubber or Caoutchouc which was, a short time back, used only
for the very insignificant purpose of rubbing out pencil marks,
is now used for almost innumerable purposes. India-rubber is the
solidified juice of several trees, such as the _Siphonia_, _Jatropha
Elastica_, _Ficus Elastica_, &c., the juice is got by making
incisions in the trunk of the trees during winter and collecting
the juice, which is caoutchouc combined with water, in the form of
a milky thick fluid, the water is then allowed to evaporate and the
India-rubber remains. It is brought here in all sorts of shapes, and
is purified before it is fit for commercial use by washing in warm
water or steaming; it is then cut into pieces and put into a kneading
machine which cuts and works it together with such rapidity that it
becomes quite hot and the pieces join into one mass. After having
undergone every kind of torture that can be well imagined in the
form of cutting, tearing, and squeezing, it is finally compressed in
a square cast iron mould, where it is kept for a time, and then is
fit for any use it has to be applied to. What is called vulcanized
India-rubber is produced by incorporating it with powdered sulphur,
or some substance containing it, as sulphuret of antimony, or the
vapour of sulphur is kneaded into the mass; this vulcanized rubber is
very elastic and does not harden by cold. Waterproof fabrics are made
by stretching the stuff to be waterproofed on a frame, at one end of
which is a partition having a slit in it, through which it is drawn,
after having been smeared with a solution of India-rubber in naptha;
the slit is so narrow that it scrapes off all superfluous caoutchouc,
it is then dried in the air.
GUTTA-PERCHA.
Gutta-percha is a substance possessing many useful and valuable
properties; it was unknown in Europe until within a very recent date,
though it is said to have been in common use, for a long period
previous to our discovery of its utility, amongst the natives of
the Indian Archipelago, chiefly for making axe-handles. It is the
concrete juice of a large tree, supposed to be the _Isonandra Gutta_,
and is brought to Europe in irregular masses of a brown color, and
contains various impurities which are easily got rid of by working
it in hot water. Gutta-percha possesses the desirable properties of
being solid, slightly elastic, not brittle, and very tough, capable
of being melted at the heat of boiling water, and being drawn out
or moulded into almost any form; it resists the action of water and
spirits, unless very strong, oils, alkalies, and weak acids, but
spirits of turpentine, chloroform, and naptha, each dissolve it. A
substance which has so many valuable properties as these, of course
enters into a multiplicity of forms and uses.
WAX.
This useful substance is produced by bees for the purpose of
building their comb, which consists of hexagonal cells made of wax;
which substance they secrete in scales, between the sections of
the abdomen, and draw out for building their beautiful cells. When
the honey is drained off from the comb, this is washed and melted,
it then constitutes the yellow wax of commerce, commonly called
“bee’s-wax.” To make this into the white wax it is boiled in water,
spread out into thin layers, and exposed to the light and air; this
is repeated until all the color has gone and the wax remains pure
and white. Pure wax is a soft-feeling substance, harder than tallow,
and not greasy to the touch; it is easily melted, and burns with a
clear white flame, hence its most general use--namely, that of making
candles; it is not soluble in water, but unites with oils and fats.
NITRE.
This substance, known also in commerce by the name of saltpetre, is
brought to this country from India, where in certain places, it forms
a sort of efflorescence on the soil; this is taken off together with
the surface of the soil, and mixed with water, which, after all the
earth has subsided holds the nitre in solution. The water is then
evaporated and the nitre crystallizes in six sided prisms.
On most parts of the continent nitre is manufactured from what are
called nitre beds, these consist of old mortar and other matters
containing lime, as the dry rubbish from old building, &c., together
with manure and other animal refuse. These beds are packed up and
kept from the rain for a certain time, when a small part of the lime
is found to be converted into nitrate of lime, this is the white
substance frequently seen to exude from newly built walls in the
form of crystals like snow. The whole mass of the nitre bed is next
washed; the water used for the first portions being poured over the
next, and so on till it is pretty rich in nitrate of lime, this is
then mixed with carbonate of potash, which decomposes the nitrate
of lime forming nitrate of potash, (nitre), and carbonate of lime,
(chalk); this last settles down and leaves the solution of nitre
clear, which is evaporated, and the nitre got pure.
Nitre is used for making gunpowder and fireworks of different kinds,
also for curing meat, especially pork and beef, to which it imparts a
red color; it is also used for making nitric acid, in the manufacture
of sulphuric acid, and as a medicine.
BLACKLEAD.
This substance, called by mineralogists “plumbago” and “graphite,”
is found in small quantities in various districts, and in a very
pure state in Cumberland. It is almost pure carbon, having but a
very slight admixture of iron; it is used to make blacklead pencils;
for coating the surface of iron, giving it a bright appearance and
preventing it from rusting; it is also used to prevent friction in
wooden machinery, and, mixed with tallow, as a lubricate for iron
machinery; blacklead, mixed with clay, is also used to make crucibles
for various purposes, these are especially adapted for melting
glasses and enamels, and are known in the trade as blue pots.
SPERMACETI.
This substance is obtained from the oily matter contained in the head
of the spermaceti whale, _Phyceter Macrocephales_, which consists of
sperm oil and spermaceti. The latter crystallizes as the mass cools,
and is afterwards purified. It is white and crystalline, is used
chiefly for candles, or mixed with oil and wax, it forms an ointment.
MANUFACTURED PRODUCTS.
SUGAR.
Illustration: (‡ SUGAR CANE FIELD.)
Sugar, like starch, exists naturally formed in many vegetables, and
has to be separated from the various foreign matters with which it is
combined; the sugar used in this country is all extracted from the
juice of the sugar-cane, _Arundo Saccharifera_, but in France a great
portion is extracted from beet-root.
The raw, or Muscovado sugar as it is called, is a brownish compound
of small crystals of sugar held together by molasses or treacle,
which gives the sugar its color and peculiar moistness; when pure,
sugar is quite white and capable of crystallization, as may be seen
in sugar candy, which is crystallized sugar; sugar, if heated,
becomes converted into a dark brown liquid called burnt sugar
or “caramel,” this has an intensely rich color, but scarcely any
sweetness; it is used to color wines and spirits. The tendency of
sugar to be converted into caramel is very great, and the whole
difficulty of sugar refining depends upon this fact, for a solution
of sugar heated is constantly changing into this substance.
To obtain the sugar from the sugar cane, it is first crushed between
powerful rollers, by which all the juice is pressed out, this is
immediately clarified by boiling it strongly with a small quantity
of slaked lime, or it would speedily ferment, it is then put into
evaporating pans, in which it is evaporated till it is ready to
crystallize or granulate; from these pans it is ladled out into a
cooler, and from thence into wooden boxes where it granulates; the
next process is called “curing” this consists of draining the sugar
of its molasses, for this purpose hogsheads or large broad barrels
are arranged on a sloping floor, and having several holes at their
lower part with a piece of plantain leaf put into them; through these
holes the molasses runs out and is collected in a vessel for the
purpose. The best kinds of sugar are partly purified by a process
called “claying;” this consists in putting the sugar into conical
earthen jars, with a hole at the point which is turned downwards;
the top is piled up with a mass of wet clay, the moisture from which
slowly sinks down, carrying with it most of the coloring matter of
the sugar; the cone of sugar is afterwards dried, broken up, and each
part ground up separately, as they form sugars of different value,
the point being the brownest and the base of the cone the whitest.
Sugar is made from the beet root in the same way as from the cane,
the roots being rasped up into a pulp by a wheel with a notched edge
acting against them. Beet-root sugar crystallizes better than cane
sugar; otherwise it is exactly like it, and purifies as well.
ALCOHOL, OR SPIRIT.
Alcohol, commonly called spirits of wine, is procured from any liquid
which has undergone the vinous fermentation, such as wine and beer.
The spirit used in England is procured from a wash made by pouring
boiling water upon ground malt, as for making beer; this, when
fermented and distilled, produces a colorless spirit, which, by being
again distilled at a gentle heat, called rectifying, produces a very
strong spirit; but even this contains some considerable quantity of
water, and to get rid of this, for certain chemical purposes, it
is necessary to add carbonate of potash, quick lime, or some other
ingredient greedy of water, and again distil it. Brandy, rum, and
whiskey, are but various forms of spirit colored and flavored with
different substances. Brandy is distilled from wine; rum from the
molasses, a sort of treacle produced in sugar making; and whiskey
from malt. The strongest brandy does not contain more than one half
of its bulk of pure spirit.
Alcohol, when pure, is a very limpid, colorless fluid, lighter than
water, in the proportion that 792 bears to 1000. It is very volatile,
boiling at 172 deg. of Fahrenheit, and highly inflammable, it
dissolves resins and volatile oils, and is, therefore, used largely
in perfumery. The well known lavender water and eau de Cologne, are
solutions of volatile oils of various kinds in pretty strong alcohol,
and what are called spirit-varnishes, are most of them solutions of
various kinds of resin in strong alcohol, although some of them, as
mastic varnish, are made with spirit of turpentine, a volatile oil,
in place of alcohol.
STARCH.
Starch exists naturally in various kinds of grain, as wheat and
barley, and in the roots and tubers of many plants, as potatoes.
The process of extracting the starch, and separating it from the
other constituents of the seed or root, consists, essentially, of
crushing it, and wishing out the starch with cold water; the liquid
resulting from this mode of treatment is of a milky whiteness, and
deposits starch by sediment. This liquid is passed through five
sieves to separate the husks and skins, and when the starch has
settled, and the liquid fermented and become sour, it is drawn off;
it is allowed to become sour as the gluten of the grain is more
completely separated by so doing. The starch is repeatedly stirred,
allowed to settle, and the water drawn off, till it is quite pure;
the top of the starch is scraped to separate any slime adhering, and
the pure starch dug out with wooden shovels and put in a box lined
with linen, in which the moisture drains off; the cakes taken from
these boxes are cut up into squares, put upon bricks, and dried by a
gentle heat; the squares are then scraped clean and packed in paper
for sale, in these packages it breaks up into pieces, so that when
they are opened, the starch has that peculiar appearance so familiar,
and almost resembling six-sided columns. Arrow-root is the starch
obtained from a West Indian plant called _Maranta Arundinacea_.
Cassava and Tapioca are starches from the manioc, and Sago, from
the sago palm. Starch, under the microscope, appears in the form
of minute globules, and is quite insoluble in cold water, in which
it falls to the bottom, leaving the water at the upper part quite
clear; but water that is nearly boiling (that is to say at 160 deg.
of Fahrenheit’s thermometer, or above), breaks or dissolves the
granules, and the starch forms with it a sort of paste, this is
the liquid used for stiffening linen and other articles in domestic
laundry.
The starch sold in this country is colored blueish by smalt or
indigo; but on the continent is used of its natural white color. If
starch be baked in an oven at the temperature of about 300 deg. it
becomes, to a great extent, soluble in cold water, forming what is
called “British gum,” this is largely used for calico printing and
other purposes; if boiled in water under great pressure, so that
the temperature can be raised to the same degree, it is also changed
into an adhesive sort of gum--this is the substance made use of
by the government authorities to spread over the backs of postage
and receipt stamps to make them adhere. The starch of grain during
germination, or growth, becomes converted into sugar; the same effect
can be produced by heating starch with diluted sulphuric acid.
SOAP.
Illustration: (‡ SOAP MAKING.)
Illustration: CUTTING SOAP.
Illustration: COPPERS FOR THE MIXING PROCESS.
This very useful article is produced by a combination of tallow or
oil with soda or potash; with soda, hard soap is formed; with potash,
soft soap. The yellow soap of commerce has also an addition of resin
or turpentine, and often palm oil, these give it its yellow color
and peculiar smell; pure white soap is made by boiling a solution of
soda with tallow or olive oil; ordinary soaps are generally made by
mixing a solution of the soda of commerce, (carbonate of soda) with
quick lime, this takes away the carbonic acid and makes the soda what
is called “caustic;” this solution is drawn off, and kitchen stuff,
tallow, turpentine, and sometimes palm oil, are added and boiled
together, until all is converted into soap, but a large quantity of
water remaining, it is necessary to separate the soap from this, for
this purpose salt is added until the water becomes so heavy that the
soap rises to the surface, whence it is removed into moulds or frames
and allowed to cool, when it is cut into bars for sale.
Illustration: FILLING YELLOW SOAP.
Illustration: MOTTLED SOAP FRAMES.
Soft soap is made in the same way, using potash instead of soda,
and, generally, a large quantity of train-oil. Castile soap is pure
soda soap, and the blueish or red mottled appearance is produced by
stirring in some sulphate of iron (green vitriol); when new it is of
a blueish color, but gets red by exposure to the air.
Oils and fats combine with the oxides of several of the metals, and
a combination of oxide of lead with olive oil forms a firm solid
substance, or plaister, which, with the addition of a little resin,
is used in surgery, and when spread upon linen or calico, forms the
common adhesive plaister.
Oils and fats all consist of a combination of organic acids,
(stearic, oleic, and margaric), with glycerine. When these fats
are boiled with soda, potash, or metallic oxides, a combination of
the oxide and fatty acid takes place, and this constitutes soap.
The glycerine is then set free, and, when purified, forms a sweet,
oily, colorless fluid, very similar to syrup, but not so sweet; it
has lately been used for several purposes, especially as a remedy
for chapped hands; a soap called “glycerine soap,” has lately been
used for the same purpose; it is a soap made without separating the
glycerine.
Illustration: MACHINE FOR CUTTING SOAP IN BARS.
The above illustration represents an ingenious contrivance for the
purpose of cutting soap.
STEARINE.
The Stearine Candles, so much in use of late, are made of what
chemists call “stearic acid.” It is extracted from tallow by the
following process:--The fat is first melted, then boiled with
water and quick lime; the lime forms a solid insoluble soap with
the stearic acid of the fat. This, when cold, is dug out of the
cistern and separated from the watery parts; it is then melted in
a wooden cistern by means of perforated iron pipes, through which
steam passes; the steam not only melts it, but condenses and runs
to the bottom, thoroughly washing it; it is again allowed to cool,
separated when it is mixed, stirred well with sulphuric acid and a
large quantity of water, and allowed to settle. This separates all
the lime, which settles to the bottom, leaving the stearine floating
on the top, from whence, when cold, it is taken and again well
washed with steam. The mass, after cooling, is cut into shavings by
a machine consisting of a wheel, having knives attached to its edge;
the shavings are put into hair-cloth bags and subjected to the most
powerful pressure by means of the hydraulic press; each hair-cloth
bag having a warm iron plate interposed between it and the next bag.
The oily parts of the mass are, by these means, all pressed out; the
remainder is again cut up and a second time pressed, leaving the pure
stearine, white and crystalline like spermaceti.
SODA.
Illustration: (‡ SODA FURNACE.)
The Soda of commerce is a carbonate of soda, and it is made from
sea salt. It is used in large quantities for the general purposes
of washing and cleansing, and very extensively in bleaching and
soap making. Soda occurs in two forms--soda ash and in crystals;
the first is the crude soda before crystallization. To make soda,
oil of vitriol (sulphuric acid) is poured, by degrees, on a layer
of sea salt, in a sort of funnel connected with a tall chimney; on
the addition of the vitriol, copious fumes of the hydrochloric acid
are given off; this is the acid formerly called spirit of salt. When
the furnace is heated and all the acid driven off, the dried residue
is taken out, it is sulphate of soda. It was formerly the custom to
allow the hydrochloric acid to pass up a very tall chimney so that
it may be dispersed in the air; but such an injurious effect was
produced on the surrounding vegetation that this could no longer be
allowed; the plan adopted was, to cause the acid to be condensed by
filling the chimney with coke, and causing water to trickle through
it; the acid vapours, coming into contact with this porous wet
surface, is condensed into a liquid, which runs down into a cistern
placed to receive it. The sulphate of soda, when taken from the
furnace and cooled, is next ground in a mill with rather more than
its weight of chalk, and about half its weight of coal. This mixture
is placed in a furnace and raised to a sufficient heat to partly
fuse it, during which time it is stirred about; the black mass which
results is called by the workmen “black ball.” It is taken out and
put into a cistern; water is then poured over it, and after stirring,
it is drained off and evaporated to a dry mass; this is impure soda.
It is mixed with coal-dust, again burnt, again washed and evaporated,
by this second process the soda ash is produced, which, being
dissolved, filtered and evaporated, produces large crystals of soda.
The large quantity of hydrochloric acid produced in the first part
of the process, is used in the of making chloric of lime. A few years
back, soda was got from the ashes of the plant called “salsola soda,”
and sold in the form of an impure carbonate called “barilla.”
WINES.
Illustration: WINE MAKING.
Wine is made from the juice of grapes. When the grapes are ripe, they
are gathered and at once put into a press, by which all the juice
is squeezed out, and the skins, stalks, and seeds left in the press.
This juice, which is called “must,” is allowed to ferment, which it
does of its own accord, in the countries where grapes most abound,
and at the season of the year when they are gathered, without the
addition of yeast or other ferment; in a few days nearly all the
sugary matter contained in the “must” becomes converted into spirit,
and it has now the pungent taste of wine; (if the wine is allowed
to ferment too long, it is very apt to become sour), the wine is now
put into casks and kept for a time, during which a slow fermentation
goes on, and that substance, which is called “tartar,” is deposited
in the form of a thick crust of an acidulus taste and brown color;
when purified till it is quite white, it forms the cream of tartar of
the druggists’ shop. The color of wine depends upon the color of the
grapes used, whether white or black.
Wine, at a general average, contains about 20 per cent. of spirit
or alcohol; when port wine is put into bottles, a slow fermentation
continues to go on, and a crust of tartar is deposited similar to
that described above, and it is the separation of this tartar which
causes port wine to improve by age.
What are called British wines, are liquids mostly made by fermenting
the juice of the fruits whose name they bear, as currant wine,
gooseberry wine, &c.; but as the climate of this country is not
favorable to the growth of grapes, or the spontaneous fermentation
of their juice, the grape wine of England is very inferior to the
foreign. The juice of any fruit required to make wine of, has to be
fermented artificially; this is generally done by making it slightly
warm, and floating on the surface a piece of bread soaked with
yeast; the wines thus produced are very apt to become sour, and it
is generally necessary to add brandy to preserve them. Many of the
British wines sold in London are made of an impure weak spirit called
“faints,” sweetened and flavored with various substances, as ginger,
orange-peel, &c. and sell for ginger or orange wine.
VINEGAR.
Illustration: (‡ VINEGAR FERMENTATION YARD.)
Vinegar is produced by fermenting and exposing to the air any liquor
which contains sugar, such as wine, infusion of malt, cyder, &c.; by
the addition of yeast, this sets up a fermentation, by means of which
the sugar in any of these liquors is converted, first into spirit,
and afterwards into vinegar; this contains a certain quantity of
acetic acid, which makes the vinegar sour. In warm countries, vinegar
is made by simply exposing the poorer kinds of wine to the sun’s
rays, when they ferment and become sour. In England, all the vinegar
produced is made by fermenting wort made of malt, this is fermented
for three or four days, and is then put into casks, with the bunghole
left open for several weeks, or until it is thoroughly sour. In
ordinary vinegar, there is about five or six parts only in the
hundred of real acetic acid, but this acid, when pure, is so strong
as to blister the skin when dropped on it; it is often extracted from
vinegar for chemical purposes, and to smell too; for when scented,
it constitutes aromatic vinegar. Vinegar, besides acid and water,
contains a little unchanged spirit, much coloring matter, and some
mucilage.
Illustration: BOILER OR COPPER.
Illustration: COOLING APPARATUS.
Vinegar is chiefly used as a condiment, and for making pickles, and
has considerable powers of preserving vegetable or animal substances;
if common vinegar be distilled, a weak colorless acid comes over,
commonly known as white or distilled vinegar. It is a common thing
to sprinkle a sick room with vinegar, under the impression that it
has disinfecting properties, but this is an error; although the
odour is very refreshing. Vinegar has, of late, been made by means
of the vinegar plant, which is a fungus, causing a species of slow
fermentation, and converting the sugar or treacle used into acetic
acid.
Illustration: FILLING CASKS.
The heading of this section gives a good idea of the large scale
on which vinegar is made; being an accurate representation of the
extensive works of Messrs. Beaufoy & Co. at Lambeth.
COAL GAS.
Illustration: (‡ COAL GAS DISTILLERY.)
Illustration: SECTION OF RETORT.
Illustration: FIG. 1. (‡ RETORT FURNACE.)
Illustration: FIG. 2. (‡ RECEIVER TUBE.)
Illustration: FIG. 3. (‡ CONDENSER.)
Illustration: FIG. 4. (‡ RESERVOIR.)
Illustration: FIG. 5. (‡ GASOMETER.)
Gas, for lighting, is made from coal, by subjecting it to heat in
iron tubes and collecting and purifying the gas which is produced;
the following is a summary of the process:--The vessels in which the
coal is put are called “retorts,” they are six or seven feet long,
one-and-a-half broad, and one high, generally fitted up six to a
furnace, in such a way that the flame may entirely surround them (see
fig. 1); from each retort an iron tube passes, and these all dip into
a large horizontal tube, reaching nearly to its bottom (fig. 2), this
is the receiver for all the gas from the retorts; it is connected
with a pit for tar and ammonical liquor, which copiously condenses
from the hot newly-formed gas.
The object of causing the tubes to dip nearly to the bottom of the
receiver is, that the fluid in it may close the end of each tube, and
so prevent the gas returning when any of the retorts are opened for a
fresh supply of coal; from the receiver, the gas passes by tubes bent
up and down inside of a great cistern of water (fig. 3) kept cold by
a constant change of its contents; this is the condenser, it causes
the separation of all the tar and ammonia that remain; but the gas is
still contaminated with sulphur, and this is got rid of by causing it
to pass into a broad iron cylinder perforated with holes and dipping
into a reservoir of lime and water mixed together and stirred about
with a machine contrived for the purpose; the gas enters this lime
mixture in hundreds of bubbles through the holes, and the sulphur
the gas contains is attracted by the lime with which it unites.
The gas now rises to the top of this reservoir, which is, of course,
air tight, and from thence passes for use to the gasometer; this is
the store-house where the gas is kept to supply the service pipes
_b_, _c_, under the streets. The gasometer is made of plates of iron
rivetted together. The lower part of this cylinder (see figs. 4 and
5) is received into a circular deep channel cut in the ground (_b b_,
fig. 5) and filled with water, so that the gasometer _d_, which is
suspended and balanced by means of the chains and weights _e e_, may
be raised or depressed at pleasure.
When the gasometer is quite down, the inside of its top, _a_, rests
on the ground; when the gas enters, it raises it up till the lower
edge is but a few inches below the water, and is prevented from
rising higher by frames which support it; when some of the weights,
_d d_, are removed, the huge cylinder, _a_, slowly sinks down and
forces the gas through the tubes, _c c_, to be burnt by thousands of
consumers. About four cubic feet of gas is produced from every pound
of coal used; the gas is lighter than air in the proportion of 650
to 1000, and it is owing to this lightness that balloons ascend when
filled with it, not from any peculiar power it has of ascending, but
because the air, being heavier, presses downwards and forces it up.
When gas is mixed with air it becomes very explosive, and when any
escape is suspected in a room, the windows of the room should be
opened _at the top_, and the door also opened, before any light is
introduced; a few minutes will then suffice to ensure safety.
One ton of good coal produces--
1 Chaldron of Coke, weighing 1494 lbs.
12 Gallons of Tar ” 135 ”
12 Gallons Ammoniacal liquor 100 ”
9500 Cubic feet of Gas, weighing 291 ”
Loss (chiefly water) ” 220 ”
--------
2240 lbs.
A cubic foot of gas weighs 514 and a-half grains.
TAR.
Illustration: (‡ TAR FACTORY.)
Tar is one of the results left in the distillation both of wood and
coal; in places where wood is plentiful and tar in request, it is
produced by burning the wood for that purpose; and in some of the
pits in which charcoal is produced, an arrangement is made to collect
the tar also. Coal-tar and wood-tar are different in some respects,
and are both distilled to procure the napthas which bear the
respective names. From wood-tar, creasöte is also extracted, and it
is this substance which gives the peculiar tarry flavor to provisions
cured or preserved by being smoked over wood fires, such as ham,
bacon, or herrings. Tar is used as a sort of paint for covering
wood-work and cordage, when much exposed to wet, which it resists
better than anything else at the same price; but the tar chiefly used
for these purposes, is that produced by burning fir or deal wood and
condensing the tar in a pit below the stack of wood, it is called
Stockholm tar, as it comes chiefly from that place.
ACETIC ACID, OR WOOD VINEGAR.
Acetic acid forms a considerable article of commerce. It is not only
used in medicine and the culinary art, but is extensively employed
in forming acetate of iron for dyeing and calico printing. To
prepare it, large iron cylinders, about eight feet long and three in
diameter, are embedded in brickwork in a row, and in such a manner
that furnaces placed below may heat them red-hot; these cylinders
have a tube leading from each into a main tube, where the liquid
products from each cylinder are received for condensation; the other
end of the cylinder has a plate of iron fitting closely to it. The
cylinders are filled with logs of wood, either oak, beech, birch, or
ash, the door is closely fastened and the joints smeared with clay;
the fires are now lighted and kept up all day, till the cylinders
are red-hot; at night they are allowed to cool. About seven or eight
hundred weight of wood is put into each cylinder. In the morning,
the charcoal, into which the wood is now converted, is withdrawn,
and a fresh charge supplied; from this charge of wood about thirty
or forty gallons of liquid is condensed in the main tube from each
cylinder, the remainder being charcoal and gases which pass off;
the liquid is acid, brown, and very offensive, and contains acetic
acid, tar, and several other ingredients, among which may be named
creasote; it is from this source all the creasote, so famous for the
cure of toothache, is obtained. The next process is to purify this
liquid; it is first distilled, and this separates much tar, it is
then mixed with lime, evaporated to dryness, and heated to expel the
remaining tar and other impurities; it is next mixed with sulphate
of soda and water and the whole stirred together, the soda, now in
unison with the acetic acid, is washed out from the lime and strained
quite clear; it is afterwards evaporated till it crystallizes, and
vitriol (sulphuric acid) then added; finally, the acetic acid is
distilled over, and the acid left in unison with the soda, forming
sulphate of soda, to be used in a similar process for the next batch
of acid; the acetic acid is now quite colorless, transparent, and
very sour, possessing a fragrant and agreeable smell. This acid is
not pure acetic acid, but contains a considerable quantity of water.
The acetic acid of commerce, mixed with seven times its bulk of
water, forms an acid of about the strength of malt vinegar, perfectly
wholesome, and, to many, more agreeable as a condiment.
Pure acetic acid may be made by mixing dry acetate of potash with oil
of vitriol in a retort, and distilling the acetic acid into a very
cold receiver; this, when flavored with various volatile oils, forms
the aromatic vinegar sold by druggists. It is a very strong acid, and
if applied to the skin will quickly blister it.
VARNISHES.
Varnishes are solutions of various resinous substances that will
dry with a bright surface on exposure to the air. They are used to
protect different substances from the action of the atmosphere, and
to give them an elegant bright surface; woods and painted work are
the chief things varnished; metals are coated with a kind of varnish
called “lacquer,” this is to prevent the bright surface of the metal
from being dulled by the air or damp, and to give an artificial
appearance to some metals; tin, for instance, if lacquered with
yellow lacquer, acquires somewhat the appearance of brass. Mastic
varnish is the varnish generally used for paper and pictures; it is
made by dissolving gum mastic in oil of turpentine. Copal varnish
is that most generally used for carriages and wood, it is made by
adding boiled linseed oil to melted copal, and afterwards thinning it
with oil of turpentine. A common varnish, fit for many purposes, may
be made by adding common resin to oil of turpentine, and warming it
till dissolved. Lacquers are made by dissolving shellac and various
other gums in strong spirits of wine, and in some cases coloring it,
either yellow, by means of gamboge, or red, by dragon’s blood (a kind
of resin). French polish is nearly the same as lacquer, but the mode
of applying it is different; the grain of the wood is first filled
up by means of drying oil and chalk rubbed in, when this becomes
thoroughly dry, a rubber of flannel is covered by a piece or two of
clean old linen, and some of the polish put on it, just enough to
moisten it, and then a little oil, this is slowly rubbed round and
round, the varnish adhering to the wood, and the oil preventing the
rubber sticking to it, and at the same time, polishing the surface of
the varnish as it dries. This process requires a good deal of art to
produce a perfect surface. Old work, before being varnished with any
varnish that contains oil (as copal varnish), should be thoroughly
freed from grease or greasy matter, or the varnish will never dry.
Good varnish should dry in twenty-four hours so that dust will not
adhere to it.
OILS.
Illustration: PRESSING LINSEED FOR OIL.
Oils, whether animal or vegetable, have pretty much the same
properties. The vegetable oils are got by crushing and pressing
certain seeds, as linseed; the animal oils are obtained chiefly
from the whale and seal tribe, or from fish, as the cod and sturgeon.
They are viscid and of a pale yellow color, lighter than water, and
therefore float upon it, and are very combustible. Oils are used for
a multiplicity of purposes: for burning in lamps, for making paints
and varnishes, preventing the friction of machinery, in making soap,
and numerous other processes. Oils are generally divided into fixed
and volatile oils; as an example of the first, linseed oil may be
selected; of the last, oil of lavender.
Some of the fixed oils are called drying oils, and it is this
kind that are used for varnish making; as linseed oil possesses
the properties of this class very perfectly, it may serve as a
description of all. Linseed oil has the power of drying when spread
out in a thin layer, becoming of a resinous consistence like varnish,
and upon this quality depends the drying powers of paint, for the
other non-drying oils, as olive oil, may be exposed to the air for
months without drying at all; the drying powers of linseed oil are
greatly increased by boiling it with litharge (oxide of lead). This
forms the drying or boiled oil used in painting, and is employed
in making varnishes, printers’ ink, and for other purposes. Oiled
silk is formed by brushing silk over with this oil and exposing it
to the air till it is dry; this oiled silk is the same that is used
for sponge-bags and bathing-caps. Of the non-drying oils, the chief
are those used for burning in lamps, as sperm oil. Salad oil is
expressed from the olive, and is called olive oil. Of the volatile
oils, the most useful is oil of turpentine, commonly called spirit of
turpentine; it is got by distilling common turpentine (the concrete
juice of trees of the fir and pine tribe), it has a strong odour,
is very inflammable, and is volatile, that is to say, if spread out,
will evaporate, leaving nothing behind; this oil is capable of mixing
with drying oils, and it not only increases their drying powers, but,
by thinning them, makes them more applicable to many purposes. Oil
of turpentine dissolves resin and many resinous substances, and forms
useful varnishes with them. Mastic varnish is mastic dissolved in oil
of turpentine; it is the varnish always used for varnishing pictures.
Many of the volatile oils are used as perfumes, and the odour of
plants and flowers depends upon the volatile oil which evaporates
from them, as lavender, cloves, and others. Peppermint water, dill
water, and cinnamon water are produced by distilling water mixed with
the substances, and is simply water containing a small quantity of
the volatile oil of these substances in solution; but eau-de-Cologne
and lavender water, although called “waters,” are mixtures of
volatile oils and spirit of wine, and contain no more water than
is comprehended in the spirit used.
INKS.
Inks are fluids of various kinds suitable for writing with pens.
The chief inks in use are black, blue, and red writing inks, and
indelible or marking ink, intended for marking linen which has to
be washed. Indian ink is not used as an ink, properly so called.
All the black inks in use are composed of green vitriol (sulphate
of iron), in union with some astringent vegetable matter, the best
is the gall-nut, although, for cheapness, logwood and oak bark have
each been used. An excellent black ink may be made by putting into
a gallon stone bottle twelve ounces of bruised galls, six ounces of
green vitriol, and six of common gum, and filling up the bottle with
rain water, this should be kept three or four weeks before using,
shaking the bottle from time to time. Blue ink has lately been much
used, it is made by dissolving newly-formed Prussian blue in a
solution of oxalic acid. To make it, dissolve some yellow prussiate
of potash in water in one vessel, and some sulphate of iron in
another, adding a few drops of nitric acid to the sulphate of iron;
now mix the two liquids, and a magnificent blue color will appear in
the form of a light sediment; this is to be put upon a paper filter,
and well washed by pouring over it warm water and allowing it to run
through; a warm solution of oxalic acid should now be mixed with it,
and the Prussian blue will dissolve into a bright blue ink.
Red ink is made by boiling chips or raspings of Brazil wood in
vinegar, and adding a little alum and gum; it keeps well, and is
of a good color. A red ink of more beautiful appearance, but not so
durable, may be made by dissolving a few grains of carmine in two
or three tea-spoonfuls of spirit of hartshorn.
Marking ink is made by dissolving nitrate of silver in water, and
then adding some solution of ammonia, a little gum water, and some
Indian ink to color it. Printers’ ink is made by grinding drying oil
with lamp-black.
CHARCOAL.
Illustration: (‡ CHARCOAL OVENS.)
Charcoal is made by burning wood in such a manner that but little
air shall be admitted during the operation, that is to say, only
sufficient to keep up the combustion of the more easily destroyed
parts of the wood, leaving a black residue called charcoal. The best
charcoal is made when the wood is quite excluded from the air, as
in making acetic acid, but where large quantities of charcoal are
used for common fuel, as in France, of course this process is too
expensive. The usual way is to pile up billets of wood and cover
the whole with turf; when fired, the wood consumes gradually and
the charcoal is left behind. Charcoal is light and porous, and of
a shining black color; it weighs about one quarter as much as the
wood used, and burns without flame or smoke, giving out a strong
heat. When charcoal burns, it combines with part of the air, and is
converted into a gas called carbonic acid, which, although invisible,
is much heavier than air, and is a deadly poison; it is therefore
necessary, where charcoal is burning, to always have some opening
at the _bottom_ of the room. Many fatal accidents have arisen from
people sleeping in a small room with a pot of burning charcoal, and
no outlet for the poisonous vapour but the chimney, up which it
will not pass on account of its weight. Charcoal enters into the
composition of gunpowder, and is used for several other purposes.
It is an excellent sweetener of foul water, and a few pieces should
always be kept in the top of the filter when the water has any
bad odour, or in the cistern or butt, where a filter is not used;
powdered charcoal has also the power of taking away the color of many
liquids, as well as the bad smell; vinegar, if warmed with powdered
charcoal, and then strained, will be almost colorless. Water butts
are sometimes burnt or charred inside, that the water may be the
better preserved in them.
Chemically considered, charcoal consists of carbon with a certain
amount of earthy matter (the ashes or earthy part of the wood
from which it was made), but these ashes may be easily removed
by maceration in an acid; the charcoal then remains unaltered in
appearance and consists of carbon, but its structure is exceedingly
porous.
CEMENTS.
In various processes, cements of different descriptions are required
for a variety of purposes. The common cement used in building, which
is called mortar, is made of sand and quicklime mixed with water.
Roman and Portland cements consist of certain kinds of clay burnt
and ground. Plaster of Paris forms a useful cement, it is to be
mixed with water to the consistence of cream, and it hardens in a
few minutes. Glue is an invaluable cement for wood and many other
purposes, it also joins any kind of broken glass or china that will
not have to be subjected to much wetting. Shellac dissolved in spirit
is a useful cement; and isinglass, dissolved in weak spirit, and
having some gum ammonicum added to it, forms the “diamond cement” for
uniting china. China and glass which require to be much wetted, are
best united by being made very hot and having the broken edges rubbed
with a piece of shellac, this melts on them, and forms, while hot,
a sort of cement; if they be immediately applied and pressed firmly
and accurately together, and then permitted slowly to cool, they will
unite so as to be almost as strong as before breaking.
COKE.
Illustration: (‡ COKE OVENS.)
Coke is produced by the partial burning of coal, in the same way
that charcoal is from wood. The great source of coke is the gas
manufactory, where it is sold in large quantities, being the result
left in the retorts after the gas has all been driven off; but the
consumption of coke by locomotive engines, &c., where coal would
not be admissible on account of the smoke produced, has become so
great that it is necessary to burn coals for its production; this
is done by a range of ovens fitted up for that purpose, having iron
doors which can be closed to any extent required so as to regulate
the draught of air. Dr. Ure gives the following in his account of
the coke ovens belonging to the London and North Western Railway
Company:--“An excellent range of furnaces for making a superior
article of coke for the service of the locomotive engines of the
London and Birmingham Railway Company, has been erected at the Camden
Town Station, consisting of eighteen ovens, in two lines, the whole
discharging their products of combustion into a horizontal flue
which terminates in a chimney-stalk one hundred and fifteen feet
high. Each alternate oven is charged, between eight and ten o’clock
every morning, with three-and-a-hall tons of good coals, a wisp of
straw is thrown in on the top of the heap, which takes fire by the
radiation from the dome, which is in a state of dull ignition from
the preceding operation, and inflames the smoke then rising from the
surface by the reaction of the hot sides and bottom upon the body of
the fuel, in this way the smoke is consumed at the very commencement
of the process, when it would otherwise be most abundant. The coke
being perfectly freed from all fuliginous and volatile matters by
a calcination of upwards of forty hours, is cooled down to moderate
ignition by sliding in the dampers and sliding up the doors, which
had been partially closed during the latter part of the process.
It is now observed to form prismatic concretions, somewhat like a
columnar mass of basalt. These are loosened by means of iron bars,
lifted out upon shovels furnished with long iron shanks, which are
poised upon swung chains with hooked ends, and the lumps are thrown
upon the pavement, to be extinguished by sprinkling water upon them
from the rose of a watering can, or they may be transferred into a
large chest of sheet iron set on wheels, and then covered up. Good
coals, thus treated, yield eighty per cent. of an excellent, compact,
glistening coke, weighing fourteen cwt. per chaldron.”
Illustration: (‡ OVEN TOOLS.)
Coke burns without smoke, and not so rapidly by far as charcoal, it
is, moreover, considerably cheaper than that article is.
GUNPOWDER.
Gunpowder is a mixture of nitre, sulphur, and charcoal, and the more
completely they are mixed, the more finely ground, and the purer they
are, the more perfect will be the gunpowder. The proportions used of
these ingredients differ slightly in different powder mills; but the
average is about seventy-four parts nitre, ten sulphur, and fourteen
charcoal, by weight; the sulphur and nitre can easily be completely
purified, but the charcoal differs very much in almost every
specimen, and charcoal that has been burnt long ago and exposed to
the air and moisture is almost unfit for the purpose, that charcoal
which has the least ash when burnt is found to be the best, and the
charcoal which has been made in iron cylinders, is better than that
made in the usual way, when each of the ingredients are separately
powdered and sifted through a kind of sieve of silk called a bolting
machine (such as is used in dressing flour), they are mixed in the
proper proportions and taken to the mill, where they are moistened
with water and ground to a smooth paste, this is pressed hard and
then broken up into pieces which are put into a copper sieve, the
bottom of which is perforated with small hole; a flat wooden ball is
put into each sieve with the pieces of damp powder, and the sieves
are all put into a circular motion by machinery, this causes the
wooden ball to turn round in the sieve and so rub the damp powder
through the little holes; it is collected below in small grains or
“corns,” this process is called “corning,” this is now dried, and
then put into a “reel” (a sort of barrel which turns round) and
the grains, by rubbing against each other, become smoothed on the
surface; the dust is now removed by a sieve, too fine to let the
grains through; the powder is now fit for use.
Gunpowder was first known in England about five hundred years ago.
It is not only used to discharge firearms, but in the more peaceful
occupations of quarrying stone, mining, and to get rid of rocks both
below and above water; these processes are called “blasting.”
GUN COTTON.
To prepare gun cotton, make a mixture of three parts sulphuric acid
and one part nitric acid; when this has cooled (for it becomes hot
on mixing), put into it some cotton wool, and let it be stirred
about with a glass rod, then taken out, and all the superfluous acid
strained from it; it is then to be covered up for an hour or so. It
should now be thoroughly washed in cold water, so that all the acid
be removed; to ensure this completely, let it be afterwards washed
in a very weak solution of potash, and then dried by a very gentle
heat, produced by either steam or hot water; when dry, soak it in
a solution of nitre and dry it again. It is now so explosive that
great care is required in its management, being about three times
as explosive as gunpowder.
PHOSPHORUS.
This substance, since the general use of lucifer-matches, has become
an important article of manufacture; whereas, but a few years ago,
it was a mere chemical curiosity. It is prepared by mixing bone ashes
with sulphuric acid, straining off the liquid part, and evaporating
it to a syrupy consistence; with this, about a quarter of its weight
of powdered charcoal is mixed, and the whole stirred and evaporated
to a dry powder; this is put into earthenware retorts, which are
connected by copper tubes to receivers filled with water; the retorts
are raised to a white heat and maintained at this high temperature
as long as any phosphorous passes into the receivers, the water in
which is kept warm, so that the phosphorous melts and runs to the
bottom, from whence it is taken and strained through chamois leather
bags, under warm water, and then cast in glass tubes into sticks.
Phosphorous is of a whitish color, like wax, is easily melted,
readily takes fire even by slight friction, and, in the air, gives
off fumes which in the dark appear luminous. It is chiefly used in
the manufacture of lucifer matches, and, mixed with flour, butter, or
sugar, is used to poison rats, mice, and other vermin, under the name
of “phosphorous paste.” Phosphorous is poison, and most dangerous
stuff to handle, minute particles often getting under the nails and
causing painful sores.
WHITE LEAD.
Illustration: WHITE LEAD BED.
Illustration: FIG. 1. (‡ LEAD GRATE.)
White Lead is used in very large quantities by painters, not only as
white paint, but to mix with and qualify every shade of color, and to
give body to them. It is prepared by different processes, and several
patents have been taken out for improvements in its manufacture; but
the most usual, and, perhaps, the best process, is as follows:--A
layer of spent tan (from the tanner’s pits) is spread out three or
four feet thick, and in it a number of earthen pots are arranged
in rows, each partly filled with a mixture of vinegar, water, and
treacle, or some other acid fermenting liquid, each of these pots is
covered with a piece of lead made in the form of a grating (fig. 1),
and over all these a flooring of boards, and then again a layer of
tan, pots covered with lead, and boards, two or three times repeated;
this is called a white lead bed, and is left for several weeks; the
tan ferments and gets warm, causing the acid vapours to rise and
corrode the lead, at the same time giving off carbonic acid. At the
end of about three months the leaden covers are found to have become
completely changed into a white shining substance (carbonate and
oxide of lead), this is washed from impurities and ground in a mill,
under water, to a fine powder. It is the white lead of commerce; but
what is familiarly called white lead, is this substance ground up
with linseed oil into a thick paste so as to be ready for the use
of painters.
White lead is a very poisonous substance, and produces the disease
called painters’ colic, when taken into the system in minute
quantities and for a long time, so that all who have much to do
with this dangerous substance, as house-painters and artists, should
be extremely careful that their hands are well washed frequently,
and especially before going to meals. Cisterns of lead, used for
containing water, very soon become coated inside with a thin film
of sulphate of lead, this prevents the water from acting further
on the lead, and the water from such cisterns is never found to be
poisonous; but, if distilled water were used, it would act rapidly on
the lead, corroding it, and causing a deposit in the water of white
lead, which would render such water dangerous in the extreme.
PRUSSIAN BLUE.
This beautiful blue color is made by mixing solutions of sulphate
of iron (green vitriol) and prussiate of potash together, when the
Prussian blue falls in the form of a precipitate, or moist powder,
of a pale greenish color, but which, by exposure to the air and
the addition of a little nitric acid, becomes intensely blue; but
the Prussian blue of commerce is never pure, for the solution of
prussiate of potash is used as it comes from the factory, before
being crystallized, and contains carbonate of potash, to get rid
of which, alum is added, and the result is, the formation of a
considerable amount of alumina, which is a white earth produced from
the alum, and which falls down in the precipitate mixed with the
Prussian blue, which is thereby increased in bulk and but little
injured in color; when a larger quantity of this alumina is purposely
produced, the result is a blue of a rather less intense color,
called “Antwerp blue.” The chemical name for pure Prussian blue is
percyanide of iron. Chinese blue is this substance in its purest
state.
PRUSSIATE OF POTASH.
Prussiate of potash is the commercial name given to what chemists
call “ferrocyanide of potassium,” it is used largely for the
production of Prussian blue, and also in the art of electro-plating,
which, of late, has greatly increased the demand for its manufacture,
and many patents have been taken out for various modifications in the
form of production, the result, however, is the same, and it occurs
in commerce in magnificent crystals of a square form, with bevelled
edges, and of a yellow color; there is, however, another kind called
the “red prussiate,” which is much used in the process of calico
printing. Prussiate of potash is made by heating together carbonate
of potash, scraps of iron, and any kind of animal refuse, as blood,
horns and hoofs, clippings of skin or old woollen rags; these are
stirred together, and the heat raised, till they form a sort of paste
of a black color, which, when cold, is thrown into water and all the
soluble parts washed out; this fluid is filtered till quite clear,
evaporated, and set aside that crystals may form; these are dissolved
and again crystallized. The red prussiate is made by passing chlorine
over the yellow prussiate in powder dissolving and crystallizing.
The most deadly of all poisons, prussic or hydrocyanic acid, is
obtained from the ferrocyanide of potassium, or prussiate of potash,
by adding diluted sulphuric acid and distilling the vapour into an
ice-cold receiver. This experiment should never be made by any but
those well conversant with such matters.
SULPHATE OF IRON.
Also called “Green Vitriol” and “Green Copperas,” is a combination
of sulphuric acid and oxide of iron, and may be made by putting iron
filings or pieces of iron into a mixture of sulphuric acid and water,
and when all action has ceased evaporating the liquid, and setting it
by till crystals form--these are of a pale green color. The sulphate
of iron of commerce is formed by exposing the iron pyrites found in
the coal districts to the air till it falls to powder; water is then
poured over this substance, and the fluid collected and evaporated.
Sulphate of iron is used chiefly to form the black dye so much in
demand to dye cloth, and also in making writing ink.
SULPHATE OF COPPER.
This substance is also known by the names, “Blue Vitriol” and “Blue
Stone.” It is a combination of sulphuric acid with oxide of copper,
and may be made by uniting those substances; but what is used on a
large scale for commercial purposes is obtained from the waters which
flow into copper mines where “copper pyrites” abound; this water
is evaporated, and the sulphate of copper crystallizes. Sulphate of
copper has of late been in great demand for the electro-deposition
of copper.
CHLORIDE OF LIME.
Chloride of lime or “bleaching-powder” is made for the purposes of
bleaching calicoes, linens, &c., and also for purifying foul air,
which it does by giving out chlorine, a gas capable of uniting with
and changing the injurious properties of foul air (which generally
contains some combination of sulphur and hydrogen). Chloride of lime
is made on the large scale by mixing hydrochloric acid with black
oxide of manganese. This mixture gives off chlorine. This is made
to pass over a layer of slaked lime, which absorbs it greedily, and
becomes converted into the bleaching powder. The hydrochloric acid
used is a product resulting from the manufacture of soda, and was
formerly wasted; it is now used in large quantities for the process
above described. “Burnett’s Disinfecting Fluid” is a solution
of chloride of zinc. It is made by dissolving scraps of zinc in
hydrochloric acid; hydrogen gas is given off, with effervescence, and
the liquid remaining is the solution of chloride of zinc, which acts
like chloride of lime, by giving off chlorine; for the chloride is
slowly decomposed by the air, the oxygen of which takes the place of
the chlorine, uniting with the zinc to form oxide of zinc, while the
chlorine is set free.
SULPHURIC ACID.
This was formerly called “Oil of Vitriol,” because it has an oily
consistence, and was originally distilled from green vitriol.
Sulphuric acid is one of the most useful chemical agents known;
scarcely a process in chemical manufacture can be performed without
its assistance. Sulphuric acid is colorless, and very heavy, being
nearly double that of water (the proportion is 1·842, while water is
1,000); it is powerfully acid, even when largely diluted with water,
and during this mixture with water gives out great heat, a mixture
of equal parts will become hotter than boiling water; if it be mixed,
however, with snow instead of water, it becomes extremely cold (below
zero).
Sulphuric acid is made by burning sulphur in a furnace, and causing
the vapours to pass into a large chamber lined with lead, and having
some water at the bottom; into this chamber the vapours arising from
nitre mixed with sulphuric acid are also admitted, together with
air and a jet of steam. These arrangements require to be properly
and nicely regulated, and it was only by study of the complicated
changes which take place between these gases (sulphurous acid, nitric
oxide, and atmospheric air), that this arrangement has been devised
and adopted, a great part of the product having been formerly wasted
in a more clumsy mode of preparation. The sulphuric acid condensed
in the water at the bottom of the leaden chamber is too weak for
use, and is concentrated by evaporating the water from it; for this
purpose it is placed in shallow leaden pans placed on the bars of a
furnace, and finally distilled in glass retorts, or retorts of iron
lined with platinum. Sulphuric acid has such a powerful attraction
for water, that an open vessel half-full of strong acid placed in
a damp situation will attract enough water from the atmosphere to
cause it to be quite full before long. This power of attracting water
has been taken advantage of to procure ice in those places where it
is not to be had naturally, as India, &c. If a vessel of water be
placed under the receiver of an air-pump, and the receiver exhausted
of air, the vapour of the water will speedily fill it, taking the
place of the air, and so stop any further evaporation; but if another
vessel containing some sulphuric acid be placed also in the receiver,
the acid will absorb the vapour of water as fast as it is formed,
and this rapid evaporation continuing produces such cold, that the
remaining water is shortly frozen. Iron and zinc dissolve rapidly
in diluted sulphuric acid, giving off abundance of hydrogen gas, and
this was the way this gas was formerly produced for the inflation of
balloons, but the common coal-gas being easily obtainable in almost
any quantity in all towns, it is now used for that purpose instead
of hydrogen gas. Sulphuric acid (chemically considered) consists
of 1 equivalent of sulphur with 3 of oxygen, and 1 of water. Pure
sulphuric acid (without water) is in the form of fine crystals, much
resembling snow, which, on exposure to air containing the slightest
quantity of moisture, absorbs it, and becomes converted into the
ordinary sulphuric acid.
If this acid (even when greatly diluted) be spilt on cotton or
linen it destroys it, producing a hole; this is owing to the acid
converting the fibre into sugar. A proposition was once made to
produce sugar from this source, but linen and cotton rags are in
too great demand for paper-making to allow of its being done.
LEATHER.
Illustration: TAN-YARD AND PITS.
Tanning is the name given to the process for converting the skins
of animals into leather, by combining them with a substance called
“Tannin.” This tannin exists in many vegetable substances, such
as oak-bark, gall-nuts, catechu, sumach, &c.: all of these, and
many more, are used for tanning, but, on account of its cheapness,
oak-bark is the usual substance employed. It is tannin which gives
the quality of astringency to many vegetables, and this very taste of
astringency is produced by a partial combination of the tannin with
the surface of the mouth.
Illustration: UNHAIRING THE SKIN.
The skins (called “hides” or “pelts”) are first freed from all loose
pieces of flesh, fat, or skin; the hair is then removed by soaking
them in lime and water. The skins are then laid in the “tan-pit”
between layers of crushed oak-bark until the pit is nearly full;
water is then pumped in, and the whole is allowed to remain for
several weeks or months (according to the thickness of the skin),
during which time, however, the skins are changed in position by
removing them from one pit to another with fresh bark in it, so that
those taken from the top of the first are placed at the bottom of
the next; and this is done from time to time, in order that all may
receive the same pressure and strength of tan-liquor. Very thick
hides take a year to tan perfectly in this way, and consequently many
processes have been tried to quicken the operation; but the leather
made most slowly seems to wear the best, and consequently fetches the
higher prices.
Illustration: DRYING ROOMS.
Skins which are thin, and to be used for fancy work, and for
book-binding and glove-making, are either tanned with “sumach,” or
with alum and salt made into a paste with flour and yolk of eggs;
this is put into a tub, and the mixture and skins worked together
with the hands till they are thoroughly united.
Illustration: SUMACH TAN TUBS.
Besides boots and shoes, leather is used for the harness of horses,
covers for seats, gloves, and innumerable other purposes.
Illustration: SPLITTING MACHINE.
For some purposes the leather is required to be very thin, and of
exactly one thickness. This is obtained by the process of splitting,
for which a machine is used whose exactness is such, that one slice
is taken from the inner part of the whole skin, reducing it in
thickness without cutting a hole in any part. The skin is stretched
tightly round a roller, which slowly revolves against a straight
knife-edge, fixed at a certain distance from it, according to the
thickness of the skin, and which is passed by the machine backwards
and forwards, cutting the skin a little further each time.
GLUE AND SIZE.
Glue is made from the clippings of hides or any other refuse of
skins, horn shavings, bones, &c. All these substances are piled up
in a boiler having a second bottom within, perforated with holes,
and kept from the true bottom by short feet; this arrangement is
to prevent the substances boiled from burning at the bottom of the
boiler. After many hours’ boiling the liquid is tested, and if it
“sets” into a sort of jelly readily, the liquor is drawn off into
another boiler, where it is kept warm, that it may not set till used.
From this boiler it is strained through flannel into square wooden
boxes, having ridges at the bottom dividing them into squares (to
direct the workmen where to cut the glue when cold); these boxes are
set apart, and when the contents have become cold and set into a
firm jelly, a knife is passed between the sides of the box and its
contents, and the glue turned out in a large solid square. This is
now cut by means of a wire with a handle at each end into squares
of about eight inches each way and an inch thick; these are now
placed on nets made of cord fixed in frames one above another in a
“drying-room,” which is open to the air at the sides, and able to
be closed up in case of wet weather. In this room the glue dries up,
shrinks, and hardens, until it is quite brittle; the marks of the net
can be seen on every square of glue.
Size is the same as glue, but instead of being dried it is put into
small barrels. Two qualities of size are made, single and double
size. It is much used by whitewashers, paper-hangers, and others,
but for any purpose requiring good size, it may be made by soaking
isinglass or gelatine in cold water till it is softened, and then
standing the vessel in boiling water till it is dissolved; this
produces a jelly nearly pure. A cheaper kind of size, almost as pure,
may be made by boiling clippings of clean parchment till they are
dissolved, and straining off the solution. Gelatine is the same as
glue, but made of materials that are clean and fresh. Isinglass is
the “sound” or swimming-bladder of the sturgeon, cleaned, dried,
and cut up into fine shreds.
PARCHMENT.
Parchment is prepared from the skins of sheep, goats, calves, and
asses. Sheep-skins furnish by far the greater part of all parchment
prepared, indeed all that which is used for deeds and law purposes.
From whatever skin prepared, it is first soaked in lime and water
to remove the hair and greasiness, and then stretched tightly on
a frame, and the surface rubbed smooth with pumice-stone, after
which the skin is allowed to dry. Parchment is used for deeds,
which require to be very durable and not easily torn, both of which
qualities it possesses much more than any kind of paper; it is also
used for book-binding, drum-heads, and many other purposes. Clippings
of parchment boiled for some time, and the liquid strained off, forms
an excellent colorless size. Vellum is a thick kind of parchment,
made chiefly of calf-skin.
CATGUT.
What is called catgut is made from the inner or lining membrane
of the intestines of sheep. These are washed, soaked, scraped, and
otherwise prepared, to render them even and clear; they are then
soaked in a solution of pearlash to clear them from grease, twisted,
exposed to the vapour of sulphur, polished by rubbing, and afterwards
stretched and dried. Catgut is used not only for the strings of
violins and other musical instruments, but also for what is called
“clock-makers’ cord,” that is to say, for the bow by which the drill
is turned, and for several other purposes. It is very strong, and
does not easily get ragged, as would any hempen cord.
PAPER.
Illustration: FIG. 1. SECTION OF RAG ENGINE, WITH DOUBLE ROLLER.
Illustration: FIG. 2. PAPER-MAKING MACHINE.
This important article of civilisation is made from rags of various
descriptions and qualities, according to the kind of paper to be
made, the finest white paper being made of old clean linen rags,
while brown paper is made of all sorts of old rope-yarns, sacking,
&c., and some kinds of paper have a considerable amount of straw
bleached and worked up in them. The rags are first sorted and cut up
into small pieces; they are then beaten on a wire screen to separate
all dust, and afterwards put into the washing-machine, through which
a stream of water runs, and in which they are kneaded and torn by
a broad wheel having iron wedges or knives fastened to its edge
(fig. 1) or surface, which work as it is turned against knives of a
similar description fastened to the bottom of the cistern. When the
rags are thoroughly washed, and at the same time torn to a coarse
pulp, it constitutes what the workmen call “half-stuff.” This is
mixed with chloride of lime, and the machine again set in motion;
this is for the purpose of bleaching the pulp; after this has been
effected, more water is turned on, as in the first washing, and all
the chloride of lime washed thoroughly away. The pulp is now either
put into another machine of the same description which cuts sharper
and finer, or else the same machine used at first is so screwed up
as to cause the knives to come more closely together; in either case
the rate of turning is greatly increased, so that the wheel turns
at about 150 revolutions per minute, and completely grinds up the
pulp till it is perfectly smooth: at this part of the process some
“indigo” or “smalt” is added if the paper is to be of a blueish tint,
as in “foolscap” paper. The “stuff” is now run off into a cistern
ready for use. Paper is now nearly all made by machinery, in pieces
of a certain width, but of an indefinite length, and is cut up into
sheets afterwards by a “cutting machine.” These machines (fig. 2)
consist essentially of a vat, A, for the pulp, which flows out on
to a bed of wire gauze, B B B, covered with felt, and bounded on
each side by straps or deckles, and forming a circle or endless band
by being stretched over a succession of rollers, C D E F G, which,
by turning round continually, move its upper surface onwards and
between other cylinders, which press out the superfluous moisture;
it is then carried forward till it arrives at several pairs of large
hollow cylinders, H H H, heated by means of steam which is passed
through them, and which compress and at the same time thoroughly dry
the paper, which comes from them as paper perfectly formed, and of
any length that may be required. It is then glazed on the surface by
the rollers I, and coiled on the cylinder L. Any name, device, or
water-mark can be worked in the bed on to which the pulp flows, and
which, being repeated at definite distances, appears on each sheet
into which the paper is afterwards cut. The apparatus marked K is to
conduct to the earth the electricity developed by the friction of the
paper against the rollers. Beneath the bed of wire gauze, on which
the pulp is laid is a cavity from which the air is pumped, and which
causes the air to press upon the surface of the pulp, and force out
a great deal of its moisture.
Illustration: FIG. 3. SIZING MACHINE.
If the paper has to be sized (which is the case in all “hard” papers)
it has to pass through a process, the machinery of which is shown in
fig. 3. A is a reservoir for size, B a trough for the paper to dip
into, C the reel of paper to be sized, D rollers to press out all
superfluous size, E a pulley to keep the paper on the stretch, F F F
a succession of hollow “drums,” to prolong the passage of the paper
through the air of the drying-room, which is heated by the furnace
G and the tubes I I. H H are openings to admit fresh air, and K
openings to allow the exit of the steam from the paper as it dries.
L is a series of rollers to glaze it.
Illustration: FIG. 4. CUTTING MACHINE.
The “cutting-machine” before referred to is represented at fig. 4.
A is a wheel upon which is fixed a plate with projections and
screws for fixing the position of the arm attached to the link B;
B link connecting the wheel A with the lever-arm G, and capable of
adjustment by means of the plate attached to the wheel A, and the
screw D; D a screw regulating the position of the rod B; E the drum
by whose motion the web of the paper is carried forward.
Illustration: FIG. 5. HAND PROCESS.
But the process, as conducted by hand (fig. 5), will give a much
better notion of how paper is formed from the pulp. A reservoir, A,
is filled with pulp, which is supplied by a wheel in the box B, to a
strainer C, and passed to a vat D, and a man, E, takes in his hands a
mould consisting of a shallow frame of wood of the size the sheet of
paper is to be, having a bottom of fine wires laid side by side, and
having wires crossing at intervals to keep them firm (the marks of
these may be seen in any sheet of laid foolscap paper held up to the
light); he dips this mould edgewise into the reservoir, and brings
it up horizontally full of pulp; this he gently shakes, to make the
pulp lie level and allow all superfluous water to drain through the
wires. It is then handed to another man H, who has a sheet of flannel
or felt spread out on a table F G, on which the mould is inverted,
and the sheet of pulp left on the flannel, which sucks up more of
its moisture; over this is placed another piece of flannel, and then
another sheet of pulp on it, and so on to the number of five or six
dozen F, then the whole is put into a powerful press, and screwed
down till all the water is squeezed out, when they are pretty firm,
and are lifted out and hung on lines to dry, after which they are
immersed in a cistern filled with thin size made by boiling clippings
of skin in water (see “Glue and Size”), and having some alum
dissolved in it--they are once more pressed and dried. What is called
“hot-pressed” paper is pressed between smooth sheets of pasteboard,
having a hot iron plate placed between every three or four dozen
sheets of paper; this gives a smooth surface to the paper. The names,
dates, and other marks seen on hand-made paper are formed by wires
worked into the bottom of the mould, which, projecting, make the pulp
thinner in those places. The water-mark of Bank-notes is made in the
same way. More than half-a-million sterling is paid annually for duty
upon paper--so vast is the consumption!
MALT.
Barley is the grain generally chosen for producing malt, although
others may be used. It is first soaked in cold water till it is
softened; it is then spread out about two feet thick on the floor of
the malt-house, where it begins to germinate, in the same manner as
if sown in the earth; this is allowed to go on so far only till the
first part of the root and stem make their appearance, in the form
of a little bud and a fibre. During germination the malt gives out
a poisonous gas called “carbonic acid,” and becomes warm, in fact it
would become too warm and be injured, but it is kept stirred by means
of wooden shovels from time to time, and the temperature ascertained
by means of a thermometer. As the process of germination goes on,
all the starchy matter naturally contained in the grain becomes
changed into sugar, and the malt, when made, has a sweetish taste.
As soon as the germination has proceeded to a certain extent it is
stopped by drying; for this purpose the malt is put into a kiln and
heated almost to scorching--if but slightly, it is called pale malt
or “amber,” if more, “brown malt” or roasted malt. Malt, if kept
dry, will remain a long time unchanged. It is used for producing
beer and vinegar, and for “wash,” from which all the raw spirit used
in England is distilled. Whiskey is also distilled in Scotland and
Ireland from malt.
Malt has the property of converting the starch of barley unmalted
into sugar while in contact with it. For example, if barley were
ground and boiling water poured on it, it would form a thick sort
of paste, which is because it contains starch only; while malt
treated in the same way, sinks to the bottom, and leaves a clear
limpid “wort,” which can be strained off, because the starch is
changed into sugar, which is soluble. Now, if equal parts of malt
and ground barley be also treated in the same way, the malt very
shortly converts the starch of the barley into sugar, and the result
is the same as if all had been malt. This was once a matter of great
importance to the brewers, who thereby saved the heavy duty imposed
upon malt.
CHOCOLATE AND COCOA.
Illustration: CHOCOLATE CRUSHING MACHINE.
Chocolate and cocoa are made from the seeds or beans of the
_Theobroma Cacao_. The fruit of this plant somewhat resembles a
cucumber, and contains from twenty to thirty seeds; these are dried
and packed for the market. They come to this country from the West
Indies (Berbice and Demerara). The beans are roasted in an iron
cylinder with holes to let out the vapour, &c.; when cool they are
deprived of their husks, and then crushed by means of rollers turning
on a flat slab, kept warm by stoves or steam. The seeds when crushed
on the warm slab become almost liquid, owing to a kind of butter or
concrete oil which they contain, and which melts by a gentle heat.
When the seeds are rolled by the machine into a smooth paste, this
is either put into a mould of tin and formed into squares and various
other forms, or left rough as it is scraped from the slab (this
is called “rock” cocoa). For chocolate it is mixed with sugar, and
either dried and powdered, or made, as the cocoa, into paste. On the
Continent it is flavoured with “vanilla.”
STEEL.
Illustration: BESSEMER’S PROCESS.
Steel is usually made by a process called “cementation.” Bars of the
best Swedish or Russian iron, about six feet long, are placed in an
iron box, the bottom of which is covered with a layer of charcoal
powder; over the first row of iron bars some more charcoal is put,
and then another row of iron bars, and so on till the box is full,
when it is carefully closed and kept at a white heat for four or
five days. When cold, the bars are found to be converted into steel,
and, being rough and blistered on the surface, are called “blistered
steel;” this is broken up, and the bars laid side by side and made
hot in a forge, where they are welded together by the blows of a
heavy hammer, and drawn or rolled out by machinery into bars of
“fine steel.” Steel differs from iron in the closeness of its grain,
in being very much “tougher,” and in having that very useful and
peculiar property called “temper,” which is the power of hardening
when suddenly cooled while red-hot. If a bar of steel as soft as
iron be made of a bright red heat, and then suddenly plunged into
cold water, it will be found to have become harder than any other
metal (so hard, indeed, that it will scratch glass), and is as
brittle and readily broken as flint or glass. If now a gentle heat
be applied to it, this extreme hardness of temper gives way. For
instance, if a piece of bright hard steel is held for a moment in
the hollow of a clear fire, a pale straw color appears on its surface,
it is now still very hard (but not so hard as before), and is fit
for razors, surgeons’ instruments, &c; but if held in the fire a
moment or two longer, it becomes of a bright golden yellow, and is
fit for penknives, and other cutting instruments; held longer still,
it becomes bright blue, and is fit for watch-springs, swords, and
other purposes requiring great elasticity but no great hardness; if
the heat be carried still further a brown tinge is seen, and it is
now rather soft, but greatly harder than iron, and is still elastic;
saws, coach-springs, and many other articles are made from steel at
this temper. If the heat be carried on to redness, the steel would be
quite soft when it had slowly cooled, but if suddenly cooled (as by
being plunged into water) the original hard temper comes back again.
Steel, like iron, may be cast, and cast-steel is one of its most
useful forms, and much resembles “fine steel.” The mode of preparing
cast-steel is to melt the “blistered steel” in a crucible, or earthen
pot, and then run it into a mould: this forms an “ingot” of steel,
which may be afterwards rolled or welded as the case may require.
Steel may be drawn into very fine wire, or wrought into the most
minute articles, as the springs and other parts of watches. It
bears a very fine and bright polish, and does not rust or tarnish so
easily as iron. It has lately been proposed to make heavy cannon of
cast-steel, which is much tougher than either cast-iron or gun-metal.
Illustration: (‡ FIG. 1. and FIG. 2.)
PERPENDICULAR SECTIONS OF CONVERTING VESSEL.
Illustration: FIG. 3. OUTSIDE VIEW OF CONVERTING VESSEL.
A process has lately been invented by Bessemer to supersede the
long and laborious process of “puddling.” It consists essentially of
transferring the melted iron into a vessel in which there are tubes
inserted at the lower part, and through which air is forced at a
great pressure, which bubbles up in streams through the melted metal,
and, as it does so, unites with the carbon and sulphur of the iron,
converting them into carbonic and sulphurous acids, and at the same
time producing an increased heat, which is quite necessary to the
success of the process, for as the iron becomes purer it also becomes
more difficultly fusible, and would set into a solid mass, but that
this greatly increased temperature keeps it fluid. This rising of
temperature is similar to what takes place upon blowing a common fire
with bellows; for the more air that is admitted to carbon raised to
a very high temperature, the more rapidly does it combine with its
oxygen, or, in other words, the more rapidly does it burn. So that,
in this process of Bessemer’s contriving, the carbon of the iron acts
as fuel to keep up the heat necessary to maintain its fusion, and
at the same time, by being converted into carbonic acid, escapes in
bubbles (like the bubbles which escape from soda-water), and this
rapid production of gas in every part of the fused iron also assists
in bringing about a thorough stirring-up and mixing together of all
its parts. Reference to the accompanying diagrams will illustrate the
working of the process. In figs. 1 and 2, A B are lower chambers,
C is the melted iron, D is an upper chamber for melting scrap-iron,
&c., E in fig. 1 and D in fig. 2 are openings for the escape of gas
and flame, F F is an air-passage running all round and communicating
by G with the tuyere-holes shown at E in fig. 4, H is the fire-brick
lining to the furnace, and I the tapping-hole through which the
fluid iron is discharged. In fig. 3, I is the tapping-hole, K the
main air-tube leading from the blast-engine, L L perpendicular tubes
(marked G in figs. 1 and 2) leading from circular air-passage to
tuyere-holes, M is an opening for the insertion of iron into the
upper chamber, opposite to opening D in fig. 2, and N the tap for
regulating the blast; O indicates the outer casing of wrought iron.
When the process is carried only to a certain point, the result is a
sort of semi-steel, which the inventor of the process expects will be
a very useful article of commerce.
Illustration: FIG. 4.
HORIZONTAL SECTION OR PLAN OF CONVERTING VESSEL.
During the bubbling up of the whole mass of iron and the extreme
elevation of temperature caused by the union of the carbon of the
impure iron with the oxygen of the air, the oxide of iron as fast as
it forms fuses into a sort of glass, and this unites with the earthy
matters of the impure iron and floats on the upper part as a flux,
thus ridding the cast-iron of all its impurities, with no other fuel
than that contained in the iron itself and the air.
The accompanying illustration represents a horizontal section or
plan of the converting vessel; A the central chamber, B a lining
of fire-bricks, C the main air-tube, D the tapping-hole, E the
tuyere-holes through which the air is forced into the melted iron
to be purified, F is the outside casing of wrought-iron.
TIN-PLATE, AND GALVANISED IRON.
What is usually called tin is, in fact, sheet-iron coated with tin,
and of this tin-plate, kettles, saucepans, &c., are made. The art
of coating iron plates with tin has been practised in England hardly
more than one hundred years. The very best soft iron is used for the
purpose of being tinned. It is rolled out into thin plates, which
are cut by shears into squares of usually thirteen inches long and
ten broad, these plates are dipped into weak acid to clean their
surfaces, then rubbed with sand, and finally washed; they are next
dipped into melted tallow, which preserves their surfaces bright
till they can be used. They are then immersed in melted tin, which
has its surface covered with melted tallow, to keep it from being
converted into oxide. When the plates have remained for a short time
in the tin, they are removed, and the superfluous tin is wiped from
the lower edge with a brush made of hemp, and then cleaned from the
grease with dry bran. The objects gained by coating iron with tin
are, increased beauty of appearance (for when tinned ware is kept
bright, it has almost the color of silver), and a protection to keep
the surface from rusting, and consequently being corroded into holes.
Copper and brass vessels are tinned inside, to prevent the formation
of that poisonous substance called verdigris. The mode of tinning
them is as follows:--They are cleaned inside by means of vitriol, and
then made hot, fine grain-tin and a little rosin being put into them,
and turned about and brushed over the surface with a ball of tow: by
this means, the tin is equally spread over the inner surface of the
vessel.
Tin-tacks, buckles, and other small articles, receive a coating of
tin by being put into an earthen pot together with some grain-tin
and a substance called “sal ammoniac,” and the pot being heated
over a fire sufficiently to melt the tin, is then shaken up till
the articles inside have received a coating of tin.
Iron plates have lately been coated with melted zinc instead of tin,
and the surface thus covered enables them to be used for various
purposes and in situations where they are exposed to the action
of the weather, as on housetops, &c. The plates, thus treated, are
called “galvanised iron,” and they are generally used in a corrugated
form. They withstand the action of the weather very much better than
simple iron plates would, for the latter would be very soon eaten
into holes from rusting.
GLASS.
This most useful and elegant material--now an article of almost
universal application, in various forms--is made on a very large
scale by fusing together sea-sand and alkali (either potash, soda,
or lime), and, in the case of “crystal,” or “flint-glass,” oxide of
lead. The following is about the composition of the chief kinds of
glass in use:--
FLINT GLASS. PARTS. PLATE GLASS. PARTS.
Pure white sea-sand 52 Pure white sand 55
Potash 14 Soda 35
Oxide of lead 34 Nitre 8
------ Lime 2
100 -----
100
CROWN GLASS. PARTS. GREEN BOTTLE GLASS. PARTS.
Fine white sand 63 Sea-sand 80
Chalk 7 Salt 10
Soda 30 Lime 10
---- ----
100 100
Flint-glass or “crystal” is very heavy, moderately soft (being
easily cut with a file), and very bright and white. It is used for
all table-glass, as decanters, wine-glasses, &c., and for the drops
or lustres of chandeliers. Plate-glass is that kind of glass now in
such general use for shop-windows, looking-glasses, &c. It is cast
on flat iron tables, and rolled out to the sizes required, then cut
and polished by machinery. In the rough state it is called “rough
plate,” and is the substance used in the Crystal Palace, and has of
late become almost a substitute for ground glass, which is simply
ordinary glass ground or roughened on the surface by means of sand,
so that it will admit light and yet not allow objects to be seen
through it. Crown-glass is the ordinary “window-glass.” It is made
in great circular pieces (see “Glass-blowing”), and cut up into the
sizes required. Crown or window-glass made some years back, had a
disagreeable tinge of green, which has been removed in modern glass
by the addition of a minute quantity of oxide of manganese.
Illustration: FIG. 1. (‡ OVERHEAD DIAGRAM OF FURNACE.)
The ingredients to be made into glass (of whatever kind it may be)
are thoroughly mixed together and thrown a little at a time into
large crucibles or melting-pots placed in a circle (A A, fig. 1) in a
furnace resting on buttresses (B B, fig. 1), and heated to whiteness
by means of a fire in the centre, C, blown by a blowing machine,
the tube of which is seen at D. This furnace is shown in perspective
in fig. 2. The ingredients melt and sink down into a clear fluid,
throwing up a scum, which is removed from time to time. This clear
glass in the fused state is now kept at a white heat till all
air-bubbles have disappeared; the heat is then lowered to a bright
redness, when the glass assumes a consistence and ductility suitable
to the purposes of the glass blower.
Illustration: FIG. 2. (‡ EXTERIOR VIEW OF FURNACE.)
Artificial gems are all but varieties of glass. What is called
“paste,” “French diamonds,” &c., are glasses of peculiar brilliancy,
well cut and polished. Garnets, emeralds, and other precious stones
are imitated by coloring the “paste” with various substances, chiefly
metallic oxides, as oxide of cobalt, which produces a blue color,
oxide of copper a red, and oxide of chromium a green color, &c.
Glass is used for a variety of purposes besides the one great purpose
of admitting light to houses while air and damp are excluded. It
furnishes an immense variety of beautiful and useful articles in
the form of drinking-vessels, vases, chandeliers, &c., and to the
chemist and manufacturer generally, it is invaluable, for vessels of
glass thoroughly resist the action of all acids (with the exception
of the hydrofluoric) and nearly every other substance. It stands
a considerable heat, and if made equal in substance and rather
thin, will not easily crack by sudden alterations of temperature.
Without glass, microscopes, telescopes, cameras, barometers and
thermometers--upon which some of our best and most useful knowledge
and some very beautiful results of chemical action depend--could
hardly have been constructed.
SODA-WATER.
Soda-water was formerly prepared by the ordinary chemist, but since
it has become so general a beverage has been made a separate branch
of chemical manufacture. Soda-water consists of a very weak solution
of carbonate of soda, holding a large quantity of carbonic acid in
solution, for water has the property of absorbing a certain quantity
of carbonic acid, and this quantity is increased in proportion to the
pressure exerted on the water. This pressure is secured in the first
place by machinery, and afterwards maintained by the bottle being
closely corked and the cork fastened in by means of wire.
Illustration: FIG. 1. SODA-WATER APPARATUS.
In fig. 1 there is an illustration of the machinery used. It
consists of a small vessel holding sulphuric acid, attached to
another vessel containing chalk and water kept constantly stirred
by a small windlass passing through a hole in the top, and working
air-tight. When some of the sulphuric acid is allowed to run into
the vessel holding the chalk an effervescence takes place, and a
rapid extrication of carbonic acid; this is conducted by a tube to
a gas-holder as a store. A tube leads from this gas-holder into a
sort of air-pump, and a man, by turning a windlass, not only works
this and thereby forces a certain quantity of gas into another vessel
of copper (plated with silver inside), but turns this vessel itself
rapidly round. In this vessel the solution of carbonate of soda is
placed, and is agitated under pressure with the carbonic acid thus
forced into it, and which it rapidly absorbs. From this vessel it
is drawn off into bottles, which are adroitly corked before much of
the carbonic acid can escape, and then wired down, a fresh supply
of solution of soda and carbonic acid being constantly introduced.
Potash-water and Carrara water are made in the same way, using potash
in the former, and chalk in the latter, instead of soda.
Illustration: FIG. 2. (‡ SODA-WATER BOTTLE.)
The form of a soda-water bottle is shown in fig. 2; it is made of
very thick glass, that it may resist the outward pressure of the
carbonic acid, and so formed that it cannot stand on its bottom, and
when laid on its side the bubble of air shall rise up to the middle
of the bottle and not to the cork, or else it would escape through
the cork before long, however nicely it may be fitted.
Illustration: FIG. 3. (‡ DISPENSING BOTTLE.)
Fig. 3 is a convenient vessel for holding about a quart of soda-water
or any other effervescing drink, all of which is not at once
required. A tube passes from the top to nearly the bottom of the
vessel, and when this is filled with aerated water, the expansive
power of the carbonic acid forces the water up this tube and out of
the spout when the handle is depressed and the tap opened, and when
sufficient is obtained, the tap can be immediately closed.
A very convenient apparatus called a “Gasogene” has lately been
constructed. It consists of a double vessel, into the upper part
of which a solution of any kind--wine and water, or even plain
water--is put, to be saturated with carbonic acid or “aerated,” and
into the lower one some carbonate of soda and tartaric acid. A tube
leads from this lower to the top of the upper vessel, which screws
on and off. By shaking the apparatus when thus charged and screwed
together, some of the liquid descends through the tube into the lower
vessel and moistens the soda and acid, which therefore act on each
other, and cause carbonic acid to be disengaged; this, rising up
through the tube (which is perforated with small holes at the upper
part), disperses itself through the liquid in small bubbles, and
causes sufficient pressure to enable the liquid to absorb it, which
therefore effervesces when drawn off by the tap and this pressure
removed.
COAL-TAR NAPTHA.
This is distilled from the coal-tar produced at the gas-house, the
residuum being pitch, and it has a very offensive smell. It is in
demand as a solvent for India-rubber, and also for use in lamps so
constructed as to require no wick, for naptha is very volatile, and
the vapour is burnt as it rises.
WOOD NAPTHA, OR PYROXYLIC SPIRIT.
This is often called wood spirit, and is procured from the tar
resulting from the distillation of wood for wood vinegar or
pyroligneous acid. It is colorless, without the disagreeable odour
of coal-tar naptha, and very inflammable, burning without smoke, very
much in the manner of spirits of wine. It is used in varnish-making,
and also for burning in lamps where heat and not light is required.
PRODUCTS OF SKILLED LABOUR.
POTTERY.
Illustration: (‡ POTTERY WORKERS.)
Illustration: STAMPERS.
Illustration: FLINT MILL.
The art of making vessels of earth is one of the oldest of all arts;
the “potter’s wheel” is frequently named in Scripture, and pottery is
found in all the remains of ancient nations. Earthenware is made from
a mixture of clay and powdered flints; the clay is freed from all its
coarser parts by being stirred with water and drawn off after the
gross matters have settled; the fluid is then allowed at leisure to
let fall the pure clay which was mixed with it, and is then fit for
use. The flints are made red-hot, and in that state thrown into cold
water, which makes them so brittle that they can be easily broken up
by the “stampers,” which are perpendicular pieces of iron made to
rise and fall with great force; the flints are then ground in a mill
to a powder, which is treated in the same way that the clay was. When
these two earths are mixed in proper proportions, and beaten together
while moist, they form a substance of the consistence of putty, a
lump of which is thrown into the centre of a piece of board turned by
means of a wheel and treadle; while turning round, it is moulded by
the hands into a rough outline of the vessel required, and afterwards
put aside to dry till it becomes of such hardness, that it can be
easily turned in a common lathe, and formed into the cup, jug or
whatever else it may be intended for. This is then baked in a “kiln”
or oven so contrived that it shall make it red-hot, and keep it so
for about two days. If it has to be ornamented with a design-such,
for instance, as the “willow pattern”--a number of prints on tissue
paper of the subject required are kept ready, and one of these is
stuck on to the vessel with the printed side next to the clay, and
rubbed smoothly on to it; after a little time the paper is washed off
with water, and the pattern is left on the vessel. The next process
is that of glazing; this is done by dipping the vessel into a mixture
generally made of ground flints and oxide of lead made into a thin
fluid with water; when the glazing is dry the vessel is once more
put into the kiln, and made red-hot, when the glazing-mixture on the
surface melts into a smooth glass. Different colours are given to
the pattern by mixing certain metallic substances with the ink used
in printing. The handles, spouts, and other projecting parts are
fixed on after turning, and before the ware is put into the kiln.
Many kinds of pottery are not turned at all, but made in a mould by
being squeezed forcibly into it; this is the case when the article
to be produced is octagonal, or possessed of any form not round, and
therefore not to be produced by turning, and when the surface has a
pattern or figures standing out in relief. Some of these are made by
filling shallow moulds with the clay, and, while moist, affixing them
to the surface, but the handles of common ware are made by forcing
some of the clay through a hole of the required form, so that it
comes out in long strips or ribands, which are cut up into lengths,
bent into the proper form, and stuck on to the ware, some softer clay
being smeared round the joint--the whole, when baked in the kiln,
becoming hard and strong.
Earthenware is often made to possess some color throughout, as drab,
yellow, brown, or black. These tints are produced by admixture of
different kinds of clay and oxides in various proportions, oxide
of iron generally giving a red or chocolate color, and oxide of
manganese a drab, brown, or black color, according to the proportion
used.
Figures, busts, and many other articles, both for ornament and
utility, are made of porcelain by casting, and are produced by
filling hollow casts of plaster of Paris with the materials for
porcelain, mixed with water to the consistence of cream--this is
called “slip,”--and when the hollow cast is filled the porous
plaster absorbs most of the moisture from the portion of liquid
“slip” next to it, so that, after a time, what remains fluid being
poured out, there is found a coating or lining of porcelain mixture
of considerable thickness adhering to the interior of the mould too
solid to be poured out; the whole is then set in a warm place to dry,
and as the porcelain shrinks as it dries, it separates itself from
the mould--which, being made of several pieces fastened together, is
taken apart without injuring the cast; after it has thoroughly dried
it is baked in a kiln or furnace. This is called “Biscuit porcelain.”
BRICKS AND TILES.
Illustration: PUG MILL.
Illustration: STOOL, OR WORKING SHED.
Illustration: BARROW FOR WET BRICKS.
Illustration: BARROW FOR DRY BRICKS.
Bricks are made of clay mixed with sand or ashes. The brick-field is
first covered with either of these to the depth of an inch or two,
and is well dug in and turned about during several weeks; when the
bricks are to be made, the mixture is put into a “pug mill;” this is
a large tub having an upright iron bar passing up from the bottom,
and having several broad iron blades fixed to its sides at the part
which is in the tub; at the top there is a cross-bar of wood, to
which a horse is harnessed; the horse, when driven round in a circle,
turns the upright iron bar and consequently the iron blades. Into
this tub the clay and ashes are now put, a little at a time, and as
the horse goes round they are thoroughly mixed together; a man takes
pieces of this clay of the proper size, and hands them to another
who stands before a table in the shed, and has a mould before him;
this consists of a piece of wood with sides of the size of the brick,
which is always ten inches long, five broad, and three thick, before
burning. The sides of this mould can be turned up and down; they are
now put up, and the piece of clay forced into the mould and scraped
off even at the top, the sides are put down, and the brick placed
carefully on a barrow, which when filled is wheeled off by another
man, and its contents arranged on the ground in long lines having a
small space between each brick, that they may not stick together and
the air may dry them. Long rows of these bricks are formed one on
the top of the other, for four or five deep, and are changed in their
position from time to time till they are quite dry and hard; they
are now ready to be burnt. This is done made by placing the bricks in
long rows, with narrow spaces between each row which are filled with
straw or twigs of wood and cinders (these cinders are got from the
ashes when they are sifted before mixing with the clay); the spaces
being filled they are covered with other bricks, and then the straw,
&c., is lighted. Layer after layer of bricks are next built up around
the fire, so that the heat shall be well kept in, and in this way the
bricks are gradually baked till they are quite hard and fit for use.
Illustration: BURNING BRICKS.
Tiles are the same as bricks, but of a different form, being flat,
and having two holes in them to receive nails. These are used to form
the roofs of houses, and are nailed on to the rafters, each layer
overlapping the one below it, so that the rain falling on the sloping
roof shall run from the top to the bottom without coming through.
Bricks have lately been made with perforations through them, which
is done by having a mould with a number of iron rods projecting from
its bottom, so that when the clay is forced on them they pass right
through it, and leave holes. The objects gained by this are two; in
the first place, the bricks are much lighter, a great advantage in
building, and in the second place they do not get so much out of form
in burning, as there is no great substance between the holes, and
therefore the shrinking takes place more evenly. Most of these bricks
are of a light straw color, and are used for facing. They are mixed
with a quantity of chalk, which is worked up with the clay, and are
not baked at such a heat as would burn it into lime.
Illustration: MIXING CHALK.
TOBACCO-PIPES.
Tobacco-pipes are made of a fine white clay, found chiefly in the
island of Purbeck, and called, from its use, pipe-clay. Dr. Ure gives
the following account of the manufacture of tobacco-pipes:--“A child
fashions a ball of clay from the heap, rolls it out into a slender
cylinder upon a plank, with the palms of his hands, in order to form
the stem of the pipe. He sticks a lump at the end of the cylinder,
for forming the bowl; which, having done, he lays the piece aside
for a day or two to get more consistence. In proportion as he makes
these rough figures, he arranges them by dozens on a board, and hands
them to the pipe-maker. The pipe is finished by means of a folding
brass or iron mould, channelled inside of the shape of the stem and
the bowl, and capable of being opened at the two ends. It is formed
of two pieces, each hollowed out like a half pipe cut as it were
lengthwise, and these two jaws when brought together constitute the
exact space for making one pipe; there are small pins in one side of
the mould, corresponding to holes in the other, which serve as guides
for applying the two together with precision. The workman takes a
long iron wire, with its end oiled, and pushes it through the soft
clay in the direction of the stem, to form the bore, and he directs
the wire by feeling with his left hand the progress of the point.
He lays the pipe in the groove of one of the jaws of the mould,
with the wire sticking in it, applies the other jaw, brings them
smartly together, and unites them by a clamp or vice, which produces
the external form; a lever is now brought down, which presses an
oiled stopper into the bowl of the pipe while it is in the mould,
forcing it sufficiently down to form the cavity, the wire in the
meanwhile being thrust backwards and forwards, so as to pierce the
tube completely through; the wire must become visible at the bottom
of the bowl, otherwise the pipe will be imperfect. The wire is now
withdrawn, the jaws of the mould opened, the pipe taken out, and
the redundant clay removed with a knife; after drying for a day or
two, the pipes are scraped, polished with a piece of hard wood, and,
the stems being bent into the desired form, they are carried to the
baking kiln, which is capable of firing fifty gross in from eight to
twelve hours. A workman and a child can easily make five gross of
pipes in a day.”
Illustration: FURNACE.
The pipes known as “meerschaum” are cut and shaped out of a natural
earth or mineral, found chiefly in the island of Samos; it is not a
clay, but consists of silica, magnesia, and lime, and is therefore
a kind of magnesian limestone. It is nearly white, very light and
porous, is easily cut with a knife, and bears a beautiful polish when
saturated with the oil of the tobacco, which at the same time gives
to the pipes a rich dark-brown color.
The meerschaum pipes sold in London are saturated with wax or grease,
to cause them to color more easily, and many are not meerschaum at
all, but are made of the dust produced in the cutting and boring
of the real meerschaum pipes, mixed up with size; these fictitious
pipes are heavier and less porous than the true meerschaum pipes, and
neither color so readily nor bear so beautiful a polish; they are,
moreover, much more easily broken.
GOLD-LEAF.
For the purpose of gilding very thin leaves of gold are required,
so thin, that although gold is expensive, yet gilded articles (as
picture-frames) are very far from being so. To produce this gold-leaf
is the business of the gold-beater. He first obtains the gold in a
state of purity from the refiner, in the form of small grains, which,
mixed with a small quantity of borax and alloy, are put into an
earthen pot called a crucible (coated beforehand with clay to keep
it from cracking), and then placed in a furnace which is raised to
a white heat. The gold, when melted, is poured into an iron mould
made warm and greased in the inside; this when cold forms an “ingot,”
which weighs two ounces, and is three-quarters of an inch square
and not quite half-an-inch thick. This ingot is now sent to the
“flattening mills,” where it is passed between sets of steel rollers
until it is rolled out into a sort of riband an inch wide and about
twelve feet long (at this degree of thinness a square inch will weigh
six-and-a-half grains). It is now cut into 150 pieces, each an inch
square, which are packed between pieces of vellum, four inches each
way, and surrounded by a sort of bag of the same material, the whole
being then subjected to the blows of a heavy iron hammer (weighing
about fourteen pounds) upon a block of solid stone, till the plates
of gold are beaten out nearly as large as the vellum, when they are
taken out and each cut into four pieces. These quarters are treated
as before, using gold-beater’s “skin” instead of vellum (this skin
is prepared from the intestines of the ox, and a set of these,
consisting of several hundreds, is called a “mould”), and the gold
again extended under the hammer to the size of the mould. The process
is repeated in the same manner a third time, after which the leaves
of gold are taken out, cut square on a cushion of leather, lifted
carefully by means of a sort of tongs made of wood, and placed in
the book. They are now between 600 and 700 times thinner than before
the beating commenced, and it would take about 280,000 of these
leaves to make the thickness of an inch. The leaves are from three
to three-and-a-half inches square, and are packed in books of paper
having the surface of the leaves rubbed with red chalk, to prevent
them from adhering to the gold; each book contains twenty-five leaves
of gold.
The different colors of gold-leaf, such as “pale gold,” “deep gold,”
or “red gold,” are produced by a small alloy of copper or silver,
the former giving a deeper and the latter a paler tinge to the pure
gold. A certain amount of alloy is always mixed with the pure metal,
otherwise it would adhere to the mould, and would not work so well.
SHOT.
Illustration: SHOT TOWER.
Illustration: SIEVE FOR MAKING SHOT.
Illustration: SECTION OF SHOT-TOWER.
Shot are made either of iron or lead. All shot for great guns or
cannon are made of iron, but for small-arms leaden balls are used,
which are cast to fit the bore of the weapon. For sporting purposes
small shot are made, of different sizes; they consist of globules of
lead with a small proportion of arsenic mixed with it--the object
of mixing arsenic is to make the shot divide better, as it has been
found by experience that lead alone does not divide so well--this
mixture, while in a fluid state, is poured through a colander or
sieve made of iron and having the bottom perforated with small holes,
to suit the size of the shot to be made. These colanders are placed
at the top of a high building like a tower, and the melted metal
runs through the perforations in fine streams and separates into
single drops as it falls. At the bottom of the building the shots are
received in vessels of water, to cool them. In these vessels all the
little globules are not exactly of the same size, although the holes
in the colanders regulate this to a certain extent, moreover they are
not all round; they have, therefore, to be sorted, which is done by
placing the shot by handfuls upon a board slightly tilted, so that
the round ones roll to the bottom and are received in a box, those
that are crooked, &c., lag behind on the board, and are put aside to
be re-melted. The shot in the box have next to be sorted as to size;
this is done by means of two sieves; the holes of one sieve are a
little larger than the size of the shot required, and this retains
therefore all that are too large, the next has holes a little less
than the shot, and this retains the right size and lets all the shot
that are too small pass through; by these simple means the shot are
separated into many sizes, which are numbered. The shot have now
to be finished, which is done by turning them, mixed with a little
black-lead, in a sort of barrel, which gives them a beautiful black
shining surface, and rubs off any roughness.
FILES.
Illustration: FILE CUTTING.
Files are among the most useful of tools for those who work in
metals, and in many other substances, as ivory, or hard woods. A file
consists of a bar of steel of various shapes, such as flat, square,
three-cornered, round, and half-round; on the surface of this bar of
steel small furrows are formed, with rough projections between them,
and these are again, in most kinds of files, crossed with others.
The mode of making a file is as follows:--A bar of wrought or cast
steel is cut off of the requisite length and of the proper figure,
and forged on an anvil to the required shape--that is to say, rather
tapering at the top and brought to a point (called the “tang”) at the
bottom, so that it may be driven into a wooden handle. The file has
now to be cut. To do this requires great manual dexterity. A man sits
before a bench, and passes a strap over each end of the file so as
to steady it, and these are kept down with the feet. A small chisel
of hard steel is held in the left hand between the thumb and finger
and struck with a short-handled heavy hammer, the effect is to cut
a notch, with an elevation at each side called a “burr;” the small
chisel is slipped up to this “burr,” and struck again, and so on till
the whole file is cut, and this with such rapidity that the eye can
scarcely follow it. When the file is thus notched from end to end, it
has to be hardened, which is done by making it red-hot and suddenly
plunging it into cold water, which makes it so hard that it will
scratch glass and cut away any other metal.
Illustration: FILE.
Illustration: RASP.
For softer substances, such as wood, a kind of file is often used
called a “rasp,” which, instead of having furrows cut on it, is
struck into little dints by means of a three-cornered piece of hard
steel, which, as it enters the file, throws up a projection also.
For filing bone and ivory, a kind of file is used with very large
notches, not crossed by others, the edge of each of which acts like
a plane-iron or chisel, and takes off shavings from the bone.
TYPE.
Illustration: TYPE CASTING.
The casting of types for printing is for the most part done by hand,
and singly, and it is one of those arts in which extreme dexterity
(only to be acquired by incessant practice) enables the founder
to accomplish an amount of labour which would seem to any one not
witnessing the process impossible. To cast each piece of type it
is necessary to dip a little ladle into a pot of melted metal,
to fill the mould, give it a sudden jerk with the left hand so as
to make the melted metal go well into the little mould, open the
mould and take the type out, shut up the mould and fasten it, and
yet a skilful workman can perform these operations five hundred
times in an hour--that is to say, rather more than eight times in
a minute--producing a type each time; this has afterwards to be
finished off by others. The metal of which type is made consists
of lead and antimony--the antimony hardens it and makes it take a
sharper impression. The letters are first cut in steel, and from
these “dies” the moulds are made in brass, by stamping, and in these
the types are cast.
Stereotype consists of plates of metal taken, by casting, from a
forme of type set up for the purpose; an impression in plaster of
Paris is first taken, and from this the metal impression is cast,
so that the original forme of type may be “distributed” or taken
to pieces, and again used, while the stereotyped impression can be
preserved for any future printing.
LUCIFER-MATCHES.
Illustration: FILLING THE BOXES.
These convenient matches, which have completely superseded the old
apparatus of flint, steel, and tinder-box, may be looked upon as
one of the improvements derived from chemistry, for phosphorus--the
necessary ingredient--till lately sold at half-a-crown an ounce;
such a price would, of course, prevent its being used for so
general a purpose as match-making. But when chemistry devised means
of preparing it on a large scale, and at a low price, then its
application was soon perceived.
Illustration: CUTTING THE MATCHES.
Illustration: FRAME.
Some years ago a kind of match was used, made of chlorate of potash
and sulphuret of antimony, and ignited by drawing through a folded
piece of glass-paper. Another sort was also for a time in use called
“Prometheans,” but far too expensive for general use. They consisted
of strips of paper rolled up, with a little glass cylinder full of
sulphuric acid sealed up in the end of each, surrounded by chlorate
of potash in powder; the end of the match had to be crushed by a
small pair of nippers, and the glass being broken, the sulphuric acid
came in contact with the chlorate of potash, causing it to take fire.
Illustration: FILLING THE FRAME.
Illustration: DIPPING THE MATCHES.
For making lucifer-matches the wood is sometimes split by hand,
and sometimes by machinery. For those the wood of which is rounded,
a peculiar apparatus is used; it consists of a plate having small
steel cylinders let into it, so that their cutting edges are raised
above the plate, and the wood is struck upon this, and not only
divided, but each piece forced through the cylinders and so rounded.
When cut, the wood is dipped in bundles into melted sulphur, and
afterwards into a composition variously made, but usually consisting
of phosphorus ground up with gum arabic and water, colored either
with red-lead or Prussian blue, and in some cases chlorate of potash
is added. This composition is spread out on a board to about the
tenth of an inch in thickness, and the matches which have been dipped
in sulphur are packed into a frame to the number of about 3000, and
dipped by pressing them on the board spread with the composition, so
that a little is attached to the ends of each match. This is a most
unwholesome and dangerous employment, and water is always at hand,
in case of fire, which is chiefly to be feared in the process of
separating them and filling the boxes when the composition has dried.
CANDLES.
Illustration: CANDLE MANUFACTORY.
Illustration: CUTTING THE WICKS.
Candles are made of either wax, spermaceti, stearine, or tallow, or
some compound or modification of these; but of whatever they may be
made, they are formed either by dipping or casting, and hence the
names “dips” and “moulds.”
Illustration: HORSE’S HEAD.
Illustration: COOLING FRAME.
When dips are to be made, a quantity of wicks of spun cotton are
prepared by a machine, and doubled so as to form a loop at the top,
through which a stick is passed. A number of wicks are arranged in
a line on each stick, and several sticks placed side by side on a
frame, which is attached to one end of a balance beam (called by the
workmen the “Horse’s Head”), with weights at the other end, according
to the weight of the candles to be made. The frame, with the wicks
upon it, is suspended over a cistern of melted tallow (kept warm by
a small fire or flue), into which it is lowered, so that the wicks
dip into the tallow; this is repeated two or three times, till a
coating of tallow is formed on the wicks, which are then placed aside
to cool while others are served in the same way, and so on, over and
over again, till each frame weighs enough to exactly counterpoise the
weight at the other end of the beam.
Illustration: CANDLE-MOULDS.
Mould candles are made by pouring melted tallow into a wooden trough
in the bottom of which pewter moulds, of the size of the candles
required, are fixed in such a way that they open into the trough by
the ends which correspond to the bottoms of the candles to be cast in
them. The other end of the mould is brought to a point, with a small
hole in it, through which the wick is passed and fastened to a stick
running along the moulds; and as the moulds are placed in two lines,
two sticks are sufficient for the trough. Melted tallow or spermaceti
is poured into the trough, and when cold the superfluous quantity
removed, and the candles drawn out of the moulds.
Wax candles are made by pouring melted wax down the wick till
sufficient has adhered to it, then rolling the candle on a marble
slab till it is even, and afterwards polishing with a cloth.
ROPE.
Illustration: SPINNING THE YARN.
Illustration: SPINNING-WHEEL.
Is a combination of the fibres of hemp or other material, so arranged
as to form a tenacious cord or band, retaining, as far as possible,
their collective strength. The first process in rope-making consists
in twisting the hemp into thick threads, called rope-yarns. This,
which resembles ordinary spinning, is commonly performed by hand, in
a rope-ground or rope-walk, an enclosed level piece of ground, about
six hundred feet in length, at one end of which a spinning-wheel
is set up, that gives motion by a band to several small rollers or
“whirls,” each of them furnished with a hook on the end of its axis
next the walk. The rope spinner carries a bundle of hemp about three
feet long round his waist, with the fibres all laid even, and having
their ends in front of him, and from these he pulls out sufficient
for the thickness of the “yarn” he is spinning, and after slightly
twisting it with his fingers, attaches it to the hook of a “whirl,”
which is set in motion by the wheel, and as the fibres are twisted he
walks backward, gradually adding more and more, a little at a time,
so as to keep the yarn of the same thickness throughout. When the
spinner has traversed the whole length of the rope-walk, he stops,
and another spinner detaches the yarn from the whirl, and it is
then wound on a reel or bobbin. The yarns being spun, they are next
“tarred” (if they are to be much exposed to wet, as for the rigging
of ships), which is done by drawing them through a kettle full of
melted tar, being wound off from one reel on to another, and the
superfluous tar wiped away by means of tow (rough hemp) fixed in a
hole through which they are drawn.
Illustration: HAWSER-LAID ROPE.
Illustration: CABLE-LAID ROPE.
What is called “laying” the rope consists in twisting a certain
number of yarns together, so as to form a strand, and these
strands into a rope. Large ropes are chiefly of two kinds, called
respectively “hawser-laid” and “cable-laid,” the latter including
only the very largest ropes. “Hawser-laid” ropes consist of a certain
number of yarns (according to the size of the rope) twisted into
a strand, and then three of these strands twisted together. The
“cable-laid” rope is composed of nine strands, that is to say, three
strands each composed of three others, and these composed of yarns,
so that three “hawser-laid” ropes, twisted together, would make one
“cable-laid” rope.
Illustration: ROPE-MAKING BY MACHINERY.
Laying the ropes and twisting the yarns into strands are both
accomplished by the same process. The yarns are attached--in
sufficient quantity for the strands--to three hooks, each turning in
the same direction, while the other ends are collected together and
turned in the opposite direction; the three hooks twist the yarns
into strands, and a hook at the other end twists the strands into
rope.
Of course, machinery of various descriptions has been applied to
rope-making, and ropes are frequently made entirely by machinery with
great rapidity. The annexed cut represents one mode of rope-making by
machinery, in which the yarn is shown being twisted into cord or rope
from the reels or bobbins on which it was wound after spinning.
WIRE.
Illustration: COARSE WIRE DRAWING.
Illustration: FIG. 1. (‡ METAL INGOT, SHEET, STRIPS.)
Illustration: FIG. 2. (‡ LARGE ROLLERS.)
Illustration: FIG. 3. (‡ CUTTING ROLLERS.)
Illustration: FIG. 4. (‡ CLOSE-UP OF CUTTING ROLLERS.)
In the manufacture of wire, the metal from which it is to be made is
first cast or wrought into an ingot (A, fig. 1); it is then passed
between rollers (fig. 2) which flatten it into a sheet (B, fig. 1),
which is next carried between other rollers (fig. 3) having their
surfaces so cut that the projections on one of them fit into the
hollows of the other, forming so many cutting edges or shears
(fig. 4), from which the sheet of metal comes forth at A, fig. 3,
cut into strips or square rods (C, fig. 1). These rods are then drawn
with great force through a plate of hardened steel having a series
of holes, gradually diminishing in size, bored through it, which is
called the “draw-plate;” the wire (of whatever metal it be) has to
be heated red-hot from time to time, to soften or “anneal” it, for
the compression produced by the drawing so hardens it that it becomes
brittle. A pair of nippers holds the end of the wire, and these are
moved along a sort of bench by a “rack and pinion” (fig. 5). When all
has passed the first hole, it is drawn through the second, and so on
to the size required. When the wire is pretty fine, it is attached
to a “cylinder,” which on turning round winds off the wire and at
the same time draws it through the plate, as shown in the engraving,
the wire being made to pass over a small charcoal fire previous to
entering the draw-plate.
Illustration: FIG. 5. (‡ RACK AND PINION.)
Illustration: FINE WIRE DRAWING.
Different metals have different powers of “ductility,” that is to
say, some can be drawn much finer than others. Dr. Turner says, “The
only metals remarkable in this respect are gold, silver, platinum,
iron, and copper. Walliston devised a method by which gold wire may
be obtained so fine that its diameter shall be only the 5000th part
of an inch, and 550 feet of it are required to weigh one grain; he
obtained a platinum wire so small that its diameter did not exceed
the 30,000th of an inch. It is singular that the ductility and
malleability of the same metal are not always in proportion to each
other. Iron, for example, cannot be made into thin leaves, but it may
be drawn into very small wires.”
Illustration: FIG. 6. (‡ WIRE GAUGE.)
The sizes of wires are ascertained by a small instrument called a
“gauge,” which is a plate of steel with an opening diminishing to
a point in it, and marks on the sides corresponding to the distance
the wire will pass down the notch (fig. 6).
CUTLERY.
Illustration: FIG. 1. (‡ KNIFE BLADE.)
Table cutlery is made in the following way. The blade is first rudely
fashioned from a flat bar of steel by the hammer and anvil, and this
is then welded to a bar of soft iron half-an-inch square, and cut
off, leaving sufficient to form the “shoulder” or “bolster,” A, and
the “tang,” B, fig. 1, which is first made by the hammer and then
beaten into a sort of mould or die. The blade is finished as far
as can be done with the hammer, made red-hot, and thrown into cold
water, which hardens the steel, and then “tempered” to a full blue
color (see “Steel”) after which it is fit for grinding. Razors and
penknife-blades are made of fine steel, and are forged and hardened
as above, but the tempering is effected by arranging them in rows
with their backs downwards on a plate of hot iron till the color
appears on their surface indicating the temper they have received,
which for razors is a pale straw color.
Cutlery is ground upon stones of different sizes, according to
the kind of article; for saws, and table-knives, which are to be
ground to a flat surface, very large stones are used, while razors,
which have a curved surface, and penknives, whose blades are very
narrow, are ground upon very small stones. These stones are driven
by machinery with great rapidity, and are arranged over a trough
of water, so that their lower parts dip into it, by which plan the
stone is kept wet; if it were used dry, the steel would get too
hot to hold, and the temper of it be injured. The article to be
ground is held at the top of the stone. When ground, the goods are
“glazed” by means of a wooden wheel the edge of which is smeared
with emery-powder, and finally, if they are to be polished (which
is only in the case of the finest steel instruments), they are held
to the edge of a wooden wheel covered with buff-leather, and charged
with “crocus”--this crocus is a red oxide of iron much used for
polishing all sorts of things, as it is both fine, free from grit,
and sufficiently hard.
Illustration: FIG. 2. (‡ BALANCE-HANDLE KNIFE.)
What are called “balance-handle” table-knives are those which when
laid on the table, will rest with the blade elevated so as not to
touch the cloth (fig. 2). The object sought in this arrangement, is
to keep the cloth from being soiled, and the manner of attaining it
is simply by making the shoulder project a little and running a small
quantity of lead into the hole of the handle before the “tang” of the
knife is introduced. The blade and handle or “haft” are united by
means of rosin, which is put in powder into the hollow of the handle,
and the tang, being made hot, is forced in, melting the rosin, and
fixing when cool.
NAILS.
Illustration: CUTTING THE METAL INTO SLIPS.
Illustration: FIG. 1. (‡ NAIL WITH SHOULDER.)
Illustration: FIG. 2. (‡ TACK.)
Illustration: FIG. 3. (‡ CLASP NAIL.)
Illustration: FIG. 4. (‡ BRADS.)
Illustration: FIG. 5. (‡ MACHINED BRADS.)
Nails are made both by hand and machinery, the former being called
“wrought,” and the latter “cut” nails. For making nails by hand, a
hammer and an anvil only are used. The “nailor,” having put several
rods of iron of the required size into the fire to get hot, that he
may use one after the other, and so lose no time, takes one out and
with the hammer beats it to a point, leaving a little shoulder (fig.
1). He then places it (at the part where the dotted line is in the
figure) on a wedge fixed to the anvil, and with a blow of the hammer
divides it; it is taken up by tongs, dropped into a hole in the
anvil, and the shoulder beaten flat; this is called a “tack” (fig.
2), for a “clasp nail” the head is made of a different form by a
particular way of striking it (fig. 3), and the form of the hole in
the anvil determines whether they shall be square or round; wrought
“brads” have the form of fig. 4. These are the principal forms of
nails, but many others are made by soldering shanks to cast heads, as
coffin-nails, and some (chiefly used by gardeners and plasterers for
driving into brickwork) are made of cast-iron. Machine-made nails are
cut by compression from a sheet of iron. Brads are cut out, simply,
as in fig. 5, which uses up the whole of the iron without any waste,
and requires no finishing; but other forms of nails are cut first
into simple wedges, and have the heads finished afterwards either by
the blows of a hammer or by compression.
Illustration: CUTTING BRADS.
Most nails are made flat or chisel-shaped at the point, that they may
not split the wood. In driving a nail with a flat point, the length
of the point should be placed across the grain of the wood, and then
it will hardly ever split it, but if otherwise, the nail, acting as a
wedge, opens the grain and splits the wood.
SCREWS.
Illustration: (‡ SCREW MOULD.)
The screws used by carpenters, smiths, and others, for fastening wood
or metal-work together, are generally made by machinery. A piece of
wire of the required thickness and length is first cut off, which is
then placed in a hole or mould, with its upper orifice “countersunk”
as in the annexed cut, and the head of the screw is formed by beating
the upper part of the piece of wire into the counter-sinking of the
mould. It is then called a “blank,” and a number of these blanks
are dropped into holes bored round the periphery of a wheel which
revolves slowly against a small circular saw driven with great
rapidity, and cutting a “thread” or slit in the head of each blank
in turn as it comes into contact with it; the wheel continuing
to revolve, each screw when it gets to the bottom drops out, so
that the holes when they again arrive upwards are ready to receive
fresh blanks. The worm, if cut by hand, is made by means of a die
of hard steel, having a hollow screw cut in it, which is screwed
slowly by a backward and forward movement on to the blank, cutting
it into a “worm;” when this is done by machinery, the die is held
fast while the screw is worked by a rotatory movement into it. The
best screws for wood are slightly tapered, which enables them to be
driven much more easily, while they hold equally fast. Large screws
for mechanical purposes are cut by a “lathe,” the bar revolving
whilst a cutter is held to it, and moved onwards by a pattern screw.
Small screws for various purposes can be easily cut by means of a
“screw-plate,” having holes of graduated sizes cut inside into hollow
screws, which is placed on the end of the wire, and gently turned
round till it is sufficiently cut.
PINS.
Illustration: PIN-MAKING MACHINE.
Illustration: COIL FOR THE HEADS.
Pins are made from brass wire drawn out in the usual manner (see
“Wire-drawing”). It is first straightened and then cut off into
lengths sufficient for two pins; these are pointed at each end
by holding them to a wheel, about two or three dozen at a time,
turning them all round at once by means of the thumb and fingers.
The wheel is not made of stone, but of steel, having the edge cut
into fine notches like a file (see “File-cutting”). After the wires
are pointed at each end, they are cut in the middle. The heads are
made by coiling some brass wire round another piece of wire exactly
the size of the pins for which they are intended, and with a sort
of chisel cutting off two of these coils at a time. The accompanying
figure represents the coil to be cut up into a string of heads, and
one of them separate. These are fixed on to the pointed wires by a
machine acting by means of a lever, by which they are compressed into
the right shape and at the same time made to hold on tightly. The
pins are then cleaned by boiling in some weak acid or a solution of
tartar, and have next to be “tinned” or “whitened,” which is done
by placing them in layers with grain-tin and cream of tartar, and
boiling them for some time till they are coated with the tin; thus
they are truly “electro-plated,” although at the time when this
process was invented no knowledge of electro-plating existed, and
the theory of the process was not understood. The pins are afterwards
cleaned and brightened by shaking them in leather bags with bran,
which is afterwards blown away by a blowing-machine; the pins are
then placed in papers (folded by a sort of crimping-machine), which
are put into a kind of vice, having a number of notches cut in it
corresponding to the number of pins to be stuck in one row, and
into these notches and through the paper ridges the pins are rapidly
passed by children.
In some manufactories pins are made entirely by machinery, and
these are the “solid-headed pins,” or pins which have the head
formed out of the same piece of wire as the body, which is chiefly
effected by compression, and in order that this may be readily
done, the wires are previously softened by heat, which is one of the
principal objections to their general use, as, in consequence of this
softening, they bend too readily.
NEEDLES.
Illustration: DRILLING THE EYES.
The manufacture of needles is one of those arts in which manual
dexterity is acquired by minute subdivision of labour, each artisan
performing only a small part of the process, but so often, that the
most wonderful rapidity and accuracy are obtained, insomuch that
although each needle has to pass through nearly 150 hands (together
with expensive machinery) before finishing, yet they may be bought
at an astonishingly low price.
Illustration: (‡ STRAIGHTENING PLATE.)
The following is an outline of the process of manufacture. The wire
is first selected, of the best steel and of a proper size, then
wound round a cylinder some fifty times, and the coil is cut in two
places opposite to each other through all the wires. These wires are
placed together in bundles several feet long, each containing about
a hundred wires, which are then cut up into lengths sufficient for
two needles by a pair of shears worked by powerful machinery. As
the wires are crooked, they have to be straightened, which is done
by packing them in bundles and enclosing them in two iron rings
so that they may be rolled forcibly backwards and forwards between
steel plates with grooves cut in them to receive the projecting
rings, and this straightens them thoroughly. The wires are next
ground to a point at each end by holding them, a dozen or two at a
time, against a revolving stone, to which they are pressed with a
piece of leather, at the same time turning or twirling them between
the thumb and fingers; when pointed, they are cut in two by a gauge
which divides them in the middle, and the blunt ends are spread out
in the form of a fan on a small anvil by the thumb and finger of
the left hand, several at one time, and flattened by the blow of a
small hammer. This flattening makes the ends too hard for piercing,
so that they have to be softened by being made red-hot and slowly
cooled; they are then pierced by children, who lay each needle on
a piece of lead and with a small punch and hammer strike out the
eye, but in nearly all cases the eye is drilled, in which case the
wire is held for an instant to the point of a small drill turned by
machinery. The groove which leads to the eye is made either by the
stroke of a small file or by compression, and the end is next rounded
off. In some needles the eyes and grooves are made by punching two
in the middle of a wire, which is afterwards divided. The needles are
tempered, by placing some thousands of them on an iron plate which
is made red-hot, and then throwing them suddenly into a vessel of
cold water; they are by this means made too hard, and have again to
be slightly heated to give the proper degree of temper and toughness
(see “Steel”), which is done by putting them in boiling oil. They
have next to be polished, and this is the most tedious part of their
manufacture. The needles, to the number of about a hundred thousand,
are packed, together with oil and emery-powder, in a strong sort of
bag, so that they all lie side by side, and several of these bags
or bundles are rolled backwards and forwards between wooden beams in
such a way that every needle rubs against others, and the friction
thus produced grinds them bright and smooth. After a time they are
taken out, and the black paste formed by the emery-powder, oil, and
steel, is cleaned off by putting them into saw-dust, and turning
them in a barrel fixed in a frame for the purpose; the saw-dust and
dirt are then blown away by a blowing-machine, and the needles again
undergo the same process several times, using finer emery-powder each
time, so as to polish them; after which they are scoured with soap
and water and wiped dry by rolling them in dry wash-leather. They are
now perfectly bright, every roughness rubbed off, and a finish being
finally given to the points by hand on a hone which turns round, they
are packed, twenty-five in each paper, for sale.
TUBING.
Tubes of lead and brass are cast in short and thick pieces, and then
drawn through holes in a draw-plate, similarly to wire, but having
a rod or “mandril” passed through the length of the tube to keep the
hollow of the right calibre.
Illustration: TUBE DRAWING.
Iron tubing for gas and water pipes, if more than about two inches
in diameter, is cast; but smaller, or “service-pipes,” are made of
wrought iron plate rolled on a mandril, and welded at the edges by
being drawn at a white heat through a draw-plate.
STEEL PENS.
Illustration: SPLITTING THE PEN.
Illustration: STAMPING THE PEN FROM THE STEEL.
Illustration: BENDING THE PEN.
Steel pens, which have almost superseded quill pens, are made in
great quantities, and, like needles and pins, can only be produced
at a sufficiently low price to meet the requirements of the people,
by those who have erected buildings and fitted up machinery so as to
make the process sufficiently rapid to be cheap. The steel is first
selected of the proper quality, and rolled out into sheets of the
thickness required and of breadth sufficient for the length of the
pens to be made; these are punched out of the proper shape by a punch
worked by a screw, which cuts out a piece at every blow, and also the
perforation which terminates the split. The maker’s name or any other
device is stamped on this flat piece of steel, called a “blank,”
which is then coiled up into the shape required (whether a “barrel”
pen or a “nib”) by a sort of press, worked by a girl, as seen in the
engraving, and the split made by a machine, also engraved. In both
these machines the screw is worked with the left hand, while the
right is engaged in placing the pens under it and pushing out the
pen with the finger after it is bent or slit, these operations, from
constant practice, being performed with great rapidity. The pens have
next to be tempered, by being made red-hot and then thrown into water
or oil, and are afterwards polished by putting them into a barrel
with fine sand, which is turned round by a windlass for several
hours. The nibs or points are then finished at a stone which turns
round, and a varnish of a brown color--made by dissolving shellac
and asphaltum in naptha--is given to the surface to keep them from
rusting. Sometimes the surface is “blued,” which is done by heating
the pens on an iron plate till the blue color appears (see “Steel”).
Pens are sometimes made of other metals besides steel, as brass, or
zinc, and sometimes of gold. Those made of gold are, of course, too
expensive for general use, but as they are never corroded by the ink,
they last a very long time, and can always be cleaned by washing; and
as the whole wear is at the point, this is tipped with an alloy which
is exceedingly hard.
ARTS AND TRADE PROCESSES.
WOOD AND PLATE ENGRAVING.
Illustration: WOOD ENGRAVING.
Engraving consists principally of two kinds, that in which the design
is made to project, and that in which it is cut in or indented; the
first kind is used in wood engraving, and in engraving metallic or
wooden blocks and cylinders for calico printing, the other is called
“plate engraving,” and is used to produce copper, steel, and zinc
plates for printing.
In wood engraving a block of box wood is used, or several pieces are
screwed or tongued together in order to make a block of the required
size, for the box wood must be cut across the grain, therefore large
blocks are not easily procured. These blocks are about an inch in
thickness, so that they may range with type and be printed with it,
they are made perfectly smooth on the face, which is rubbed with a
little flake-white and Bath brick, to give it a whitish and slightly
roughened surface. On this prepared surface the design is drawn with
a black-lead pencil, and the block is then put into the hands of the
engraver, who cuts away--to the depth of about one-twentieth of an
inch--all those parts which have not been blackened by the pencil,
leaving every line and dot of the drawing projecting, and this serves
as a sort of stamp or type, to print from. (See “Printing.”) In this
way the illustrations to the present work are produced.
In plate engraving the design is copied from the original and cut
into the plate in a manner quite opposite to that of engraving on
wood; for every line intended to be printed, instead of projecting,
is cut in with a sharp edge, so that they may be filled with ink,
instead of being covered, as in wood engraving. When the design is
formed entirely by lines, it is called “line engraving,” and when
formed by dots, it is said to be “stippled,” and these two kinds are
often combined in the same plate. There is a process for engraving
plates, called “etching,” by which the lines or dots on the plate
are not made by cutting, but are corroded or eaten in by the chemical
action of nitric acid; and few plates are now produced by the graver
alone, the design being first etched and afterwards finished off by
the graver, but some are produced by etching alone, whence they are
called “etchings.” The process of etching is as follows:--The surface
of the plate is made smooth and bright, then heated, and afterwards
coated with a mixture of asphaltum, wax, and mastic--called
“etching-ground”--a ball of which is tied up in a piece of silk,
rubbed over the hot plate, and dabbed with a dabber till a smooth
layer or coating is formed all over it; it is “smoked” over the flame
of a candle, to blacken it, and the result is a smooth black varnish,
which covers the surface of the plate, and is capable of resisting
the action of nitric acid. On this surface the design is drawn with
an “etching-point,” a steel instrument which cuts or scratches quite
through the etching-ground, exposing the surface of the copper at the
bottom of each scratch. When the design is finished--in hues or dots,
according to the style required--a ridge or border of wax is made
all round the plate so as to form it into a sort of shallow tray, and
into this the nitric acid, mixed with a little water, is poured, and
carefully watched till in the judgment of the engraver it has bitten
into the plate sufficiently for the fainter parts of the design.
The acid is then poured off, and the plate washed and dried, after
which the parts intended to remain most lightly etched are stopped
out with varnish, and the acid again poured on, to corrode the lines
left exposed to its action more deeply. This is repeated two or three
times, according to the nature of the design, when the plate is again
heated, to melt the etching-ground, and the whole is cleaned off with
turpentine. The plate may now be used to print from, or it may be
further finished by the “graver,” “burnisher,” or “dry point,” which
is simply a point of steel used to make very fine and faint scratches
instead of cuts, for the graver cuts out the piece of copper, while
the dry point merely indents it.
There is another kind of plate engraving, called “mezzo-tinto.” This
is done by first covering the whole plate with a rough granulated
surface--called a “mezzo-tint ground,”--by means of a sort of notched
chisel, called a “cradle” or “grounding-tool,” which is rocked to
and fro over the surface in every possible direction, till the whole
is covered with minute dots; so that if it were then used to print
from, it would produce an even dark surface. On this ground the
engraver works with a “scraper,” scraping gradually away all those
parts which are to appear as lights in the finished picture, and the
more the ground is scraped away the lighter will be the tint, till,
finally, those parts which are to be quite white are scraped smooth
and burnished, so that they shall hold no ink at all. In this way the
engraver proceeds till his design is finished, trying the effect from
time to time. This kind of engraving is often combined with etching,
producing greater sharpness of outline than mezzo-tint alone.
LITHOGRAPHY.
Illustration: LITHOGRAPHIC PRESS.
This is the art of producing designs upon stone in such a manner
that impressions may be printed from them. It is often miscalled
“engraving on stone;” properly speaking, it is not engraving, but a
process depending on the want of affinity between watery and greasy
matters, the design being made with a greasy substance, either in
the form of ink or crayon called “lithographic chalk,” as follows.
A close-grained stone called lithographic stone (a kind of magnesian
limestone) is ground perfectly even on the surface, and (if for being
written upon) polished with pumice-stone, or (if for being drawn upon
with chalk) grained with fine sand; the design is drawn with chalk
or ink, each of which is made up of greasy materials--wax, soap,
and asphaltum, colored with lamp-black. When the design is made,
the stone is etched--washed over with a weak mixture of nitric acid
and water--which answers three purposes; it very slightly bites away
the stone in all places except where it is covered with the ink or
chalk, it smoothes the grain in the same places, and it converts the
soap of the ink or chalk into grease. We have now the surface of the
stone quite wet, except where the design is, which, being greasy,
keeps quite dry. The stone, placed in a press, is rolled over with a
roller smeared with greasy printing ink, which will not adhere to the
wet stone, but it readily does to all parts of the design; a piece
of paper is placed over the stone, and a flap of leather covers it;
along this leather the scraper of the press is brought very forcibly
when it is worked, and on removing the paper an impression is found
to be transferred to it from the stone. This process is repeated
again and again, many hundred times, without much injury to the
original design.
Colored lithography, called chromo-lithography, is produced by using
several stones consecutively (each transferring a separate color), so
that the design shall be complete when the whole are printed.
PRINTING.
The art of printing consists in producing impressions from a pattern
or types--cut out and projecting, or engraved and indented--by
smearing the projecting parts or filling up the indented markings
with ink, so that impressions, to any number, and exactly resembling
each other, may be taken from them. Printing is comparatively a
modern invention, although impressing or taking impressions from
seals is one of the very oldest. It is divided into two kinds,
plate-printing and surface-printing. Printing from type or blocks
having the marks to be impressed raised, is called surface-printing,
while that in which the lines or marks are cut in, is called
plate-printing.
Illustration: PRINTING-PRESS.
Illustration: INKING-TABLE.
In surface-printing, when types are used, they are packed up closely
into masses and wedged together in iron frames, so that they form,
as it were, solid blocks; the types or wood-blocks when required to
be printed from are
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