Buffon's Natural History. Volume 10 (of 10)
by comte de Georges Louis Leclerc Buffon · English · Gutenberg #45868 · 482,399 chars · public domain (US)
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Title: Buffon's Natural History. Volume 10 (of 10)
Author: comte de Georges Louis Leclerc Buffon
Editor: James Smith Barr
Release date: June 3, 2014 [eBook #45868]
Most recently updated: October 24, 2024
Language: English
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*** START OF THE PROJECT GUTENBERG EBOOK BUFFON'S NATURAL HISTORY. VOLUME 10 (OF 10) ***
_Barr's Buffon._
------
Buffon's Natural History.
CONTAINING
A THEORY OF THE EARTH,
A GENERAL
_HISTORY OF MAN_,
OF THE BRUTE CREATION, AND OF
VEGETABLES, MINERALS,
_&c. &c._
FROM THE FRENCH.
WITH NOTES BY THE TRANSLATOR.
IN TEN VOLUMES.
========
VOL. X.
========
London:
PRINTED FOR THE PROPRIETOR,
AND SOLD BY H. D. SYMONDS, PATERNOSTER-ROW.
1807.
T. Gillet, Printer, Crown-Court, Fleet-Street.
CONTENTS.
OF
THE TENTH VOLUME.
_Page_
_Of the Degeneration of Animals_ 1
Nature and Properties of Minerals, Vegetables, &c.
_Light, Heat, and Fire_ 27
_Of Air, Water, and Earth_ 75
_Experiments on the Progress of Heat in Mineral Substances_ 109
_A Table of the Relations of different Mineral Substances_ 135
_Observations on the Nature of Platina_ 156
Experiments on Light, and on the Heat it can produce.
_Invention of Mirrors to burn at great distances_ 193
_Observations and Experiments on Trees and other Vegetables_ 245
_On the Temperature of the Planets_ 279
General Views of Nature.
_First View_ 325
_Second View_ 343
BUFFON'S NATURAL HISTORY.
_OF THE DEGENERATION OF ANIMALS._
The deer-kind whose horns are a sort of wood, and of a solid texture,
although ruminating, and internally formed like those whose horns are
hollow and porous, seem to form a separate family, in which the elk is
the trunk, and the rein-deer, stag, axis, fallow-deer, and roe-buck,
are the lesser and collateral branches; for there are only six species
of animals whose heads are armed with branched horns that fall off and
are renewed every year. Independently of this generic character, they
resemble each other still more in formation and natural habitude; we
should, therefore, sooner expect mules from the stag or fallow-deer,
joined with the rein-deer or the axis, than from a union of the stag
with the cow.
We might be still better authorised to regard all the different kinds
of sheep and goats as composing but one family, since they produce
together mules, which immediately, and in the first generation, ascend
to the species of sheep. We might even add to this numerous family
of sheep and goats those of the gazelles and bubalus, which are not
less in number. The muflon, the wild goat, the chamois, the antelope,
the bubalus, the condoma, &c. seem to be the principal trunks of this
genus, which contains more than thirty different species, and the
others are only accessory branches which have retained the principal
characters of the stocks from which they issued; but which, at the same
time, have prodigiously varied by the influence of the climate, the
difference of the food, and by the state of slavery to which man has
reduced most animals.
The dog, the wolf, the fox, the jackal, and the isatis, form another
genus, the different species of which resemble each other so strongly,
especially in their internal conformation, and in the organs of
generation, that it is difficult to conceive why they do not intermix.
From the experiments which I made to form a union of the dog with the
wolf and fox, the repugnance to copulate seemed to proceed from the
wolf and fox rather than from the dog, that is, from the wild animal
and not from the tame; for those bitches which I put to the trial would
readily have permitted the wolf and fox, whereas the females of the
two latter would never suffer the approaches of the dog. The domestic
state seems to render animals less faithful to their species: It
gives them also a greater degree of heat and fecundity, for the bitch
generally produces twice a year, while the females of the wolf and fox
litter only once; and it is to be presumed, that those dogs which have
been left in desert countries, and which have so greatly multiplied in
the island of Juan Fernandes, and in the mountains of St. Domingo, &c.
produce only once a year, like the wolf and the fox. This circumstance,
if it were proved to be the fact, would fully establish the unity of
genus in these three animals, which resemble each other in conformation
so strongly as to oblige us to attribute their repugnance to some
external circumstances.
The dog seems to be the intermediate species between the fox and the
wolf. The ancients have stated, that the dog, in some countries, and
under particular circumstances, engenders with the wolf and fox. I was
desirous of verifying this assertion, and although I did not succeed
in the trials I made, yet we must not conclude that it is impossible,
for my experiments were with captive animals; and it is known that in
some species captivity alone is sufficient to extinguish desire, and
to give them a repugnance to copulation, even with their own kind;
consequently they would still more refuse to unite with individuals
of another species: but I am persuaded, that when in a state of
freedom, and deprived of his own female, the dog would unite with the
wolf and fox, particularly if he had become wild, lost his domestic
cast, and approached the manner and natural habits of these animals.
The fox and wolf, however, never unite, though they live in the same
climate and country, but support their species pure and unmixed; we
must, therefore, suppose a more ancient degeneration than history has
recorded, if they ever belonged to one species; it was for this reason
I asserted that the dog was an intermediate species between the fox and
wolf; and his species is also common, since it can unite with both; and
if any thing could shew that they all three originally sprang from the
same stock, it is this common affinity between the dog, the fox, and
the wolf, and which seems to bring their species nearer than all the
conformities in their figures and organization. To reduce the fox and
wolf, therefore, into one species, we must return to a state of nature
very ancient indeed; but in their present condition, we must look upon
the wolf and fox as the chief trunks in the genus of the five animals.
The dog, the jackal, and the isatis, are only lateral branches placed
between the two first; the jackal participates of the dog and wolf, and
the isatis of the jackal and fox. From a great number of testimonies
it appears that the jackal and the dog engender easily together; and
it is observable, from the description and history of the isatis, that
it almost entirely resembles the fox in its form and temperament,
that they are equally found in cold countries, but that, at the same
time, it inclines to the jackal in its disposition, continual barking,
clamorous voice, and the habit of always going in packs.
The shepherd's dog, which I have considered as the original stock of
every other dog, is, at the same time, that which approaches nearest
in figure to the fox. He is of the same size, and, like the fox, he
has erect ears, a pointed muzzle, and a strait trailing tail. He
also approaches the fox in voice, sagacity, and instinct. The dog,
therefore, may originally have been the issue of the fox, if not in
a direct, at least in a collateral line. The dog, which Aristotle
calls _canis-laconicus_, and which he affirms to have proceeded from
an union of the fox and dog, might, possibly, be the same as the
shepherd's dog, or, at least, it has more relation to him than to
any other dog. We might, therefore, be inclined to imagine, that the
epithet _laconicus_, left uninterpreted by Aristotle, was only given
to this dog because he was found in Laconia, a province of Greece; and
of which Lacedæmon was the capital; but if we attentively consider the
origin of this _laconic_ dog we shall perceive that the breed was not
confined to the country of Laconia, alone but must have been found in
every country where there were foxes; and this induces me to presume,
that the epithet _laconicus_ might possibly have been used by Aristotle
in a moral sense, to express the brevity and acuteness of his voice,
because he did not bark like other dogs, but had a shorter and shriller
note, like that of the fox. Now our shepherd's dog is that to which we
can justly apply this term of _laconic_, for of all dogs his voice is
the sharpest and most rarely employed. Besides, the characters which
Aristotle gives to his _laconic_ dog agree with those of the shepherd's
dog, and perfectly persuade me they are the same.
The genus of cruel and rapacious animals is one of the most numerous
and most diversified; evils here, as in other cases, seem to be
produced under every shape, and to assume various natures; the lion
and the tiger, being detached species, rank in the first line; all the
others, as the panther, the ounce, the leopard, the lynx, the caracal,
the jaguar, the cougar, the ocelot, the serval, the margai, and the
cat, compose only one cruel family, whose different branches are
more or less extended and diversified according to the difference of
climate. All these animals resemble each other in natural dispositions,
although they are very different with respect to size and figure.
They all have sparkling eyes, short muzzles, and sharp, crooked, and
retractile claws. They are all destructive, ferocious, and untameable.
The cat, which is the last and the least species, although reduced
to slavery, continues its ferocity, and is no less perfidious. The
wild cat has preserved the character of the family, and is as cruel
and mischievous as any of his larger kindred. They are all equally
carnivorous, and enemies to other animals. Man, with all his art and
power, has not been able to annihilate them: fire, steel, poison,
pits, and every method has been used against them without attaining
that point. As the individuals are very prolific, and the species
numerous, the efforts of man have been limited to keeping them at a
distance, and confining them in the deserts, whence they never sally
without spreading terror, and making great depredations. A single tiger
issuing from the forest is sufficient to alarm a multitude of people,
and oblige them to take up arms. What then would be the consequence
if these sanguinary animals came in numbers, like wolves or jackals,
to commit their depredations? Nature has given this instinct to timid
animals, but fortunately denied it to the bold tribes; they go singly,
and depend upon their courage and strength for their safety and
support. Aristotle observed, and justly remarked, that of all animals
furnished with talons not any of them are sociable, or go together in
troops.[A] This observation, which was then confined to four or five
species only, being all that were known in his time, is extended and
verified over ten or twelve other species since discovered. Other
carnivorous animals, such as the wolf, the fox, the dog, the jackal,
and the isatis, whose claws are straight, go mostly in troops, and are
all timid, and even cowardly.
[A] Nullum animal cui ungues adunci, gregatile esse perpendimus. Arist.
Hist. Anim. Lib. i. Cap. 1.
By thus comparing every quadruped, and ranking each with its proper
genus, we shall find, that the two hundred species of which we have
given the history, may be reduced to a small number of families, or
principal stems, from which it is not impossible all the others have
derived their origin.
To place this reduction in a regular method, we shall observe that
all the animals of the two continents, as well as all those peculiar
to the Old World, may be reduced to fifteen genera, and nine solitary
species. These genera are, first, the whole hoofed genus, properly
so called, which includes the horse, the zebra, and the ass, with
all the prolific and barren mules. 2. The large cloven-hoofed with
hollow horns, as the ox and the buffalo, with their varieties. 3. The
small cloven-hoofed animals with hollow horns, such as the sheep,
the goat, the gazelle, the antelope, and every other species which
participates of their nature. 4. The cloven-hoofed with solid horns,
which are shed and renewed every year; this family contains the elk,
the rein-deer, the stag, the fallow-deer, the axis, and the roe-buck.
5. The ambiguous cloven-hoofed, which is composed of the wild boar,
and all the varieties of the hog, such as that of Siam, with a hanging
belly, that of Guinea, with long ears, pointed and turned backwards,
and that of the Canary islands with thick and long tusks, &c. 6. The
very extensive race of digitated carnivorous animals with crooked and
retractile claws, in which we must comprehend the panther, leopard,
guepard, ounce, serval, and cat, with all their varieties. 7. The
digitated carnivorous animals with straight and fixed claws, which
include the wolf, fox, jackal, isatis, and the dog, with all their
varieties. 8. The digitated carnivorous animals with fixed claws, and
a pouch under their tails. This consists of the hyæna, civet, zibet,
badger, &c. 9. The digitated carnivorous animals with long bodies, five
toes to each foot, and the great toe, or thumb, divided from the rest;
this genus is composed of the ferret, martin, pole-cat, weasel, sable,
ichneumon, &c. 10. The numerous family of digitated quadrupeds which
have two large incisive teeth in each jaw, and no bristles on their
bodies; this contains the hare, rabbit, and every kind of squirrels,
dor-mice, marmots, and rats. 11. The digitated quadrupeds, whose bodies
are covered with spiny quills, as the porcupine and hedge-hog. 12. The
digitated animals covered with scales, as the long and short-tailed
manis, or scaly lizards. 13. The amphibious digitated genus, which
includes the beaver, otter, musk-rats, walrus, and seals. 14. The
four-handed genus, which comprehends the apes, baboons, monkeys,
makis, loris, &c. 15. The winged quadrupeds, which includes bats, &c.
with all their varieties. The nine detached species are the elephant,
rhinoceros, hippopotamus, giraffe, camel, lion, tiger, bear, and mole,
which are all subject to a greater or smaller number of varieties.
Of those fifteen genera, and nine detached species, seven genera, and
two species are common to both continents. The two species are, the
bear and the mole; and the seven genera are, 1. The great cloven-hoofed
with hollow horns, for the ox is found in America, under the form of
the bison. 2. The cloven-hoofed, with solid horns, for the elk exists
in Canada, under the name of original; the rein-deer, under that of
caribou; and stags, fallow-deer, and roe-bucks, are found in all the
provinces of North America. 3. The digitated carnivorous animals with
fixed claws; for the wolf and fox are found in the New World as well as
in the Old. 4. The digitated animals with long bodies, as the weasel,
martin, and pole-cat, are met with in America as well as in Europe. 5.
We find also in America, part of the digitated genus with two large
incisive teeth in each jaw, as the squirrels, marmots, rats, &c. 6.
The digitated amphibious genus, as the walrus, seal, beaver, and otter,
exist in the North of the New Continent. 7. The winged genus exist also
in America, as the bat and vampire.
There remains, therefore, only eight genera, and five detached species,
which are peculiar to the Old Continent. These eight genera are, 1.
The whole-hoofed, properly so called, for neither the horse, ass,
zebra, nor mule, were met with in the New Continent. 2. The small
cloven-hoofed beasts with hollow horns; for sheep, goats, gazelles, or
antelopes existed in America. 3. The family of hogs; for the species
of wild boar is not to be found in America; and although the pecari,
and its varieties, are related to this family, yet they differ in a
sufficient number of remarkable characters to justify their separation.
4. It is the same with carnivorous animals with retractile claws; we do
not meet with either the panther, leopard, guepard, ounce, or serval,
in America; and although the jaguar, couguar, ocelot, and margai, seem
to belong to this family, there is not, one of these species of the
New World found in the Old, nor one of the Old to be met with in the
New. 5. The same remark may be applied to the digitated quadrupeds
whose bodies are covered with prickles; for although the coendou and
the urson approach very nigh to this genus, nevertheless, these species
are very different from those of the porcupine and hedge-hog. 6. The
digitated carnivorous genus with fixed claws, and a pouch under the
tail; for the hyæna, civets, and the badger, do not exist in America.
7. The four-handed genus; for neither apes, baboons, monkeys, nor
makis, have ever been seen in America. The sapajous, sagons, opossums,
&c. although quadrumanous, yet they essentially differ from those of
the Old Continent. 8. The digitated genus whose bodies are covered with
scales; for none of the scaly lizards are found in America, and the
ant-eaters, to whom they may be compared, are covered with hair, and
differ too much from the scaly lizards to be considered of the same
family.
Of the nine detached species, seven, namely, the elephant, rhinoceros,
hippopotamus, giraffe, camel, lion, and tiger, are found only in
the Old World; and two, viz. the bear and mole, are common to both
continents.
If we, in the same manner, enumerate the animals which are peculiar to
the New World, we shall find, that there are about fifteen different
species which may be reduced to ten genera and four detached species.
These four species are the tapir, the cabiai, the lama, and the pecari;
but there is only the tapir we can absolutely term detached; for the
pecari has varieties; and the pacos may be united to the lama, and
the Guinea hog to the cabiai. The ten genera are, 1. Eight species
of sapajous. 2. Six species of sagoins. 3. The opossums, phalangers,
tarsiers, &c. 4. The jaguars, couguars, ocelots, margais, &c. 5. Three
or four species of coatis. 6. Four or five species of mouffettes. 7.
The agouti genus, which comprehends the acouchi, the paca, the aperea,
and the tapeti. 8. That of the armadillos, which consists of seven or
eight species. 9. Two or three species of ant-eaters; and, 10thly, The
sloth, of which we are acquainted with but two species.
Now these ten genera, and four detached species, to which the fifty
species of animals peculiar to the New World may be reduced, though
they differ from those of the Old Continent, nevertheless have some
relations which seem to indicate some common affinity in their
formation, and lead us to causes of degeneration, more ancient than any
of the rest. We have already made the general remark, that all animals
of the New World were much smaller than those of the Old. This great
diminution in size, whatever maybe the cause, is a primary kind of
degeneration, which could not be made without having a great influence
on the figure of the animal, and we must not lose sight of this effect
in comparing them together.
The largest is the tapir, which though not bigger than the ass, can
only be compared with the elephant, rhinoceros, and hippopotamus; he
claims the first place for size in the New Continent, as the elephant
does in the Old. Like the rhinoceros, his upper lip is muscular and
projecting; and, like the hippopotamus, he often enters the water.
In some respects he represents them all three, and his figure, which
partakes more of the ass than of any other animal, seems to be as
degraded as his stature is diminished. The horse, the ass, the zebra,
the elephant, the rhinoceros, and the hippopotamus, had no existence
in America; neither was there an animal in this New Continent which
could be compared with them, either with respect to size or figure. The
tapir appears to have some affinity to the whale, but he is so mixed,
and approaches so little to any one of them, that it is not possible
to attribute his origin to the degradation of any particular species.
And, notwithstanding these trifling relations which he is found to have
with the rhinoceros, the hippopotamus, and the ass, we must look on him
not only as a peculiar species, but even as a single genus.
The tapir, therefore, does not belong to any species of the Old
Continent, and scarcely does he bear any characters which approximate
him to those animals with which we have just been comparing him. The
nature of the cabiai is likewise averse from our comparison: externally
he has no resemblance with any other animal, and only approaches the
Indian hog of the same continent, by his internal parts, and both
species are absolutely different from all those of the Old Continent.
The lama and the pacos appear to have more significant marks of their
ancient parents: the first with the camel, and the second in the sheep.
The lama, like the camel, has a long neck and legs, slender head, and
the upper lip divided. He resembles the latter also by his gentle
manners, servility of disposition, endurance of thirst, and aptness
for labour. This was the first and most useful domestic animal of the
Americans: they made use of him to carry burdens, in the same manner
as the Arabs do the camel. Here therefore are sufficient resemblances
in the nature of these animals, to which we can yet add the permanent
marks of labour; for though the back of the lama is not deformed by
hunches like that of the camel, he, nevertheless, has callosities on
his breast, occasioned by the like habit he is used to of resting on
that part of his body. Yet, notwithstanding all these affinities, the
lama is a very distinct and different species from the camel. He is
much smaller, not exceeding a fourth or a third part of the camel's
magnitude. The shape of his body, and the quality and colour of his
hair, are also very different. His temperament is still more so; for
he is a phlegmatic animal, and delights only to live on the mountains,
whereas the camel is of a dry temperament, and willingly inhabits the
most scorching sands. On the whole, there are more specific differences
between the camel and the lama, than between the camel and the giraffe.
These three animals have many characters in common, by which they
might be referred to one genus, but, at the same time, they differ so
much in other respects, that we cannot suppose them to be the issue of
one another; they are, therefore, only neighbours and not relations.
The height of the giraffe is nearly double that of the camel, and
the camel double that of the lama. The two first belong to the Old
Continent, and form separate species. The lama, therefore, which is
only found in the New, must be a distinct species from both.
It is not the same with respect to the pecari, for though a different
species from the hog, he, nevertheless, belongs to the same genus. He
resembles the hog in shape, and every external appearance, and only
differs from it in some trifling characters, such as the aperture on
his back, shape of the stomach, intestines, &c. We might, therefore, be
led to suppose that this animal sprung from the same stock as the hog,
and that he formerly passed from the Old World to the New, where, by
the influence of the soil, he had degenerated to so great a degree as
now to constitute a distinct species.
With regard to the pacos, though it appears to have some affinities
with the sheep, in its wool and habit of body, yet it differs so
greatly in every other respect, that this species cannot be looked
on either as neighbours or allies. The pacos is rather a small lama,
and has not a single mark which indicates its having passed from one
continent to the other. Thus of the four detached species peculiar to
the New World, three, namely, the tapir, the cabiai, and the lama, with
the pacos, appear to belong originally to this continent, whereas the
pecari, which forms the fourth, seems to be only a degenerated species
of the hog, and to have formerly derived its origin from the Old
Continent.
By examining and comparing, in the same manner, the ten genera, to
which we have reduced the other animals peculiar to South America, we
shall discover, not only singular relations in their nature, but marks
of their ancient origin and degeneration. The sapajous and sagoins bear
so great a resemblance to the monkeys, that they are commonly included
under that name. We have proved, however, that their species, and even
their genera, are different. Besides, it would be very difficult to
conceive how the monkeys of the Old Continent could assume in America
a different-shaped visage, a long, muscular, and prehensile tail,
a large partition between the nostrils, and other characters, both
specific and generic, by which we have distinguished and separated them
from the sapajous. But as the monkeys, apes, and baboons, are only
found in the Old Continent, we must look upon the sapajous and sagoins
as their representatives in the New, for these animals have nearly
the same form, as well externally as internally, and also have many
things in common in their natural habits and dispositions. It is the
same with respect to the makis, none of which are found in America,
yet they seem to be represented there by the opossums, or four-handed
animals, with pointed muzzles, which are found in great numbers in the
New Continent, but exist not in the Old. We must, however, observe,
that there is much more difference between the nature and the form of
the makis, and of these four-handed American animals, than between the
monkeys and the sapajous; and that there is so great a distance between
the opossums and the maki that we cannot form an idea that the one
ever proceeded from the other, without supposing that degeneration can
produce effects equal to those of a new nature; for the greatest number
of these American four-handed animals have a pouch under the belly, ten
incisive teeth in each jaw, and a prehensile tail; whereas the maki has
a flaccid tail, no pouch under the belly, and only four incisive teeth
in the upper jaw, and six in the lower; therefore, though all these
animals have hands and fingers of the same form, and also resemble each
other in the elongation of the muzzle, yet their species, and even
their genera, are so different, that we cannot imagine them to be one
and the same issue, or that such great and general disparities have
ever been produced by degeneration.
On the other hand, the tigers of America, which we have indicated by
the names of jaguars, couguars, ocelots, and margais, though different
in species from the panther, leopard, ounce, guepard, and serval, of
the Old Continent, are, nevertheless, of the same genera. All these
animals greatly resemble each other, both externally and internally;
they have also the same natural dispositions, the same ferocity, the
same vehement thirst for blood, and what approximates them still nearer
in genus, those which belong to the same continent differ more from
each other than from those of the other Continent. For instance, the
African panther differs less from the Brasilian jaguar than the latter
does from the couguar, though they are natives of the same country. The
Asiatic serval, and the margai of Guiana, likewise differ less from
one another than from the species peculiar to their own continents.
We, therefore, may justly suppose, that these animals had one common
origin, and that, having formerly passed from one continent to the
other, their present differences have proceeded only from the long
influence of their new situation. The mouffettes, or stinkards, of
America, and the pole-cat of Europe, seem to be of the same genus. In
general, when a genus is common to both continents the species which
compose it are more numerous in the Old than in the New; but in this
instance it is quite the reverse, for there are four or five kinds
of pole-cats in America, while we have only one, the nature of which
is inferior to that of all the rest; so that the New World, in its
turn, seems to have representatives in the Old; and if we judged only
from the fact, we might think these animals had taken the opposite
road, and passed from America to Europe. It is the same with respect
to some other species. The roe-bucks and the fallow-deer, as well as
the stinkards, are more numerous, larger, and stronger in the New
Continent than in the Old; we might, therefore, imagine them to be
originally natives of America; but as we cannot doubt that every animal
was created in the Old Continent, we must, consequently, admit of
their migration from the Old to the New World, and at the same time
suppose, that instead of having degenerated, like other animals, they
have improved their original nature by the influence of the soil and
climate.
The ant-eaters, which are singular animals, and of which there are
three or four species in the New World, seem also to have their
representatives in the Old. The scaly lizards resemble them in the
peculiar character of having no teeth, and of being obliged to put out
their tongues and feed upon ants; but if we would suppose them to have
one common origin, it is strange, that instead of scales, with which
they are covered in Asia, they are clothed with hair in America.
With respect to the agoutis, pacos, and other animals of the seventh
genus peculiar to the New Continent, we can only compare them with the
hare and rabbit, from which, however, they all differ in species. What
renders their being of a common origin doubtful is, the hare being
dispersed almost over every climate of the Old Continent, without
having undergone any other alteration than in the colour of its hair.
We cannot, with any foundation, therefore, imagine that the climate of
America has so far changed the nature of our hares to so great a degree
as to make them tapetis or apereas, which have no tail; or agoutis with
pointed muzzles, and short round ears; or pacos, with a large head,
short ears, and a coarse hair marked with white stripes.
On the whole, the coatis, the armadillos, and the sloths, are so
different, not only in species, but also in genus, from every animal
of the Old World, that we cannot compare them with any one; it is
also impossible to refer them to any common origin, or attribute to
the effects of degeneration the prodigious differences found in their
nature from that of every other animal.
Thus, of ten genera, and four detached species, to which we have
endeavoured to reduce all the animals peculiar to the New World, there
are only two, the genus of the jaguars, ocelots, &c. and the species
of the pecari, with their varieties, which can with any foundation
be connected with the animals of the Old Continent. The jaguars and
ocelots may be regarded as a species of the leopard or panther, and
the pecari as a species of hog. After these are five genera and one
detached species, namely the species of the lama, and the genera of
sapajous, sagoins, stinkards, agoutis, and ant-eaters, which may be
compared, though in a very distant and equivocal manner, with the
camel, monkey, pole-cat, hare, and scaly lizards. There then remain
four genera and two detached species, namely, the opossums, the
coatis, the armadillos, the sloths, the tapir, and the cabiai, which
can neither be referred nor compared to any genera or species of the
Old Continent. This sufficiently proves that the origin of these
animals, peculiar to the New world, cannot be attributed merely to
degeneration. However, great and powerful the effects of degeneration
may be supposed, we cannot, with any appearance of reason, persuade
ourselves that these animals were originally the same as those of the
Old Continent. It is more reasonable to imagine that the two continents
were formerly joined, and that those species which inhabited the New
World, because they found the climate and soil most suitable to their
nature, were separated from the rest by the irruption of the sea when
it divided Asia from America. This is a natural cause, and similar ones
might be conceived which would produce the same effect; for example, if
the sea should make an irruption from the eastern to the western side
of Asia, and thus separate the southern parts of Africa and Asia from
the rest of the Continent, all the animals peculiar to the southern
countries, such as the elephant, the rhinoceros, the giraffe, the
zebra, the orang-outang, &c. would be, relatively to the others, the
same as those of South America at present are; they would be entirely
separated from the animals of the temperate countries, and could not
be referred to an origin common to any of the species or genera which
inhabit these countries, on the sole foundation that some imperfect
resemblances, or distant relations, might be observed between them.
We must, therefore, to find out the origin of these animals, turn back
to the time when the two continents were not separated, and refer to
the first changes which happened on the surface of the globe. We must,
at the same time, place before our view the two hundred species of
quadrupeds as constituting thirty-eight families; and although this is
not the state of nature, such as it is come down to us, and as we have
represented it, but, on the contrary, a much more ancient state, which
we can only attain by inductions and relations nearly as fugitive as
time, which seems to have effaced their traces, we have endeavoured, by
facts and monuments still existing, to return to those first ages of
nature, and to exhibit those epochas which appear to be most clearly
indicated.
AND PROPERTIES OF MINERALS, VEGETABLES, &c.
LIGHT, HEAT, AND FIRE.
All the powers of Nature with which we are acquainted, may be reduced
to two primitive forces; the one which causes weight, and that which
produces heat. The force of impulsion is subordinate to them; it
depends on the first for its particular, and on the latter for its
general effects. As impulsion cannot exercise itself but by the means
of a spring, and the spring only acts by virtue of the force which
approximates the remote parts, it is clear, that to perform its
power it has need of the concurrence of attraction: for if matter
ceased to attract, if bodies lost their coherence, every spring would
be destroyed, every motion intercepted, and every impulsion void;
since motion cannot transmit itself from one body to another but by
elasticity, it is demonstrable, that one body absolutely hard and
inflexible, would be absolutely immoveable, and entirely incapable
of receiving the action of another. Attraction being a general and
permanent effect, impulsion, which in most bodies is neither constant
nor fixed, depends on it as a particular effect; for, if all impulsion
were destroyed, attraction would still equally subsist and act; it is,
therefore, this essential difference which makes impulsion subordinate
to attraction in all inanimate and purely passive matter.
But this impulsion depends still more immediately, and generally, on
the power which produces heat; for it is principally by the means
of heat, that impulsion penetrates organized bodies; it is by heat
that they are formed, grow, and develope themselves. We may refer to
attraction alone all the effects of inanimate matter; and in this same
power of attraction, joined to that of heat, every phenomena of live
matter. By live matter I understand not only every thing that lives,
or vegetates, but also every living organic molecule, dispersed in the
waste or remains of organized bodies. In it I comprehend also light,
heat, fire, and all matter which appears to be active in itself. Now
this live matter always tends from the centre to the circumference,
whereas brute or inanimate matter tends from the circumference to the
centre. It is an expansive power which animates the live matter, and
it is an attractive force to which the inanimate matter is obedient.
Although the directions of these two powers be diametrically opposite,
yet they balance themselves without ever being destroyed, and from the
combination of these two powers equally active, all the phenomena of
the universe result.
But it may be said, by reducing all the powers of Nature to attraction
and expansion, without giving the cause of either, and by rendering
impulsion, (which is the only force whose cause is known and
demonstrated to our senses) subordinate to both, do you not abandon
a clear idea, and substitute two obscure hypotheses in its place? To
this I answer, that as we know nothing except by comparison, we shall
never have an idea of what general effect will produce, because such
an effect belonging to every thing, we should be unable to compare it
to any, and consequently there is no hope of ever knowing the cause or
reason why all matter attracts, although we are sensible such is the
fact. If, on the contrary, the effect were particular, like that of the
attraction of the loadstone and steel, we might expect to discover the
cause, because it might be compared to other particular effects. To ask
why matter is extended, heavy, and impenetrable, are ill-conceived
propositions, and merit not an answer; it is the same with respect
to every particular property, when it is essential to the subject,
and we might as well be interrogated why red is red? The philosopher
becomes a child when he puts such questions; and however much they may
be forgiven to the last, the former ought to exclude them from his
thoughts.
It is sufficient that the forces of attraction and expansion are two
general, real, and fixed effects, for us to receive them for causes
of particular ones; and impulsion is one of these effects, which we
must not look upon as a general cause, known and demonstrated by our
senses, since we have proved that this force of impulsion cannot exist
nor act, but by the means of attraction, which does not fall upon our
senses. Nothing is more evident, nay, certain, than the communication
of motion by impulsion; it is sufficient for one body to strike another
to produce this effect. But even in this sense, is not the cause of
attraction most evident, and that motion, in all cases, belongs more to
attraction than impulsion?
The first reduction being made, it might perhaps be possible to adduce
a second, and to bring back the power even of expansion to that of
attraction, insomuch that all the forces of matter would depend solely
on a primitive one; at least this idea seems to be worthy of that
sublime simplicity with which nature works. Now cannot we conceive
that this attraction changes into repulsion every time that bodies
approach near enough to rub together, or strike one against the
other? Impenetrability, which we must not regard as a force, but as a
resistance essential to matter, not permitting two bodies to occupy
the same place, what must happen when two molecules, which attract the
more powerfully as they approach nearer, suddenly strike against each
other? Does not then this invincible resistance of impenetrability,
become an active force, which, in the contact, drives the bodies with
as much velocity, as they had acquired at the moment they touched? And
from hence the expansive force will not be a particular force opposed
to the attractive one, but an effect derived therefrom. I own, that we
must suppose a perfect spring in every molecule, and in every atom of
matter, to have a clear conception how this change of attraction into
repulsion is performed. But even this is sufficiently indicated by
facts; the more matter is attenuated, the more it takes a spring. Earth
and water, which are the most gross aggregates, have a less spring
than air; and fire, which is the most subtle of all the elements, is
also that which has the most expansive force. The smallest molecules
of matter, the smallest atoms with which we are acquainted are those
of light, and we are sensible of their being perfectly elastic, since
the angle under which the light is reflected, is always equal to that
under which it comes. We may therefore infer, that all the constitutive
parts of matter in general, are a perfect spring; and that this spring
produces all the effects of the expansive force, every time that bodies
strike by meeting in opposite directions.
We know of no other means of producing fire, but by striking or rubbing
bodies together[B]; since by supposing man without any burning glasses,
and without actual fire, he will have no other means of producing it;
for the fire produced by uniting the rays of light, or by application
of fire already produced, had the same origin.
[B] The fire, which arises from the fermentation of herbs heaped
together, and which manifests itself in effervescences, is not an
exception that can be opposed to me, since this production of fire
depends, like all the rest, from the action of the shock of the parts
of matter one against the other.
Expansive force, therefore, in reality might be only the re-action
of the attractive, a re-action which operates every time that the
primitive molecules of matter, always attracted one by the other,
happen immediately to touch; for then it is necessary, that they be
repelled with as much velocity as they had acquired in a contrary
direction, at the moment of contact; and when these molecules are
absolutely free from all coherence and only obey the motion alone
produced by their attraction, this acquired velocity is immense in the
point of contact. Heat, light, and fire, which are the greatest effects
of expansive force, will be produced every time that bodies are either
artificially or naturally divided into very minute parts, and meet in
opposite directions; and the heat will be so much the more sensible,
the light so much the more bright, the fire so much the more violent,
according as the molecules are precipitated one against the other with
more velocity by their force of mutual attraction.
From the above it must be concluded, that all matter may become
light, heat, and fire; and that this matter of fire and light is
not a substance different from every other, but preserves all its
essential qualities; and even most of the attributes of common matter,
is evidently proved by, first, light, though composed of particles
almost infinitely minute, is, nevertheless, still divisible, since
with the prism we separate the rays, or different coloured atoms one
from another. Secondly, light, though in appearance endowed with a
quality quite opposite to that of weight, that is, with a volatility
which we might think essential, is, nevertheless, heavy like all
matter, since it bends every time it passes near other bodies, and
finds itself inclined to their sphere of attraction. It is very
heavy, relatively to its volume, which is very minute, since the
immense velocity with which light moves in a direct line, does not
prevent it from feeling sufficient attraction near other bodies, for
its direction to incline and change in a manner very sensible to our
eyes. Thirdly, the substance of light is not more simple than all
other matter, since it is composed of parts of unequal weight; the red
rays are much heavier than the blue; and between these two extremes
there are an infinity of intermediate rays, which approach more or
less the weight of the red, or the lightness of the blue according to
their shades. All these consequences are necessarily derived from the
phenomena of the inflection of light, and of its refraction, which, in
reality, is only an inflexion which operates when light passes across
transparent bodies. Fourthly, it may be demonstrated, that light is
massive, and that it acts, in some cases, as all other bodies act;
for, independently of its ordinary effect, which is to shine before
our eyes, and by its own action, always accompanied with lustre, and
often with heat, it acts by its mass when it is condensed, and it acts
to the point of putting in motion heavy bodies placed in the focus of a
good burning glass: it turns a needle on a pivot placed in its focus:
it displaces leaves of gold or silver before it melts or even sensibly
heats them. This action, produced by its mass, precedes that of heat:
it operates between the condensed light and the leaves of metal in
the same manner as it operates between two other bodies which become
contiguous, and, consequently, have still this property in common with
all other matter. Fifthly, light is a mixture, like common matter, not
only of more gross and minute parts, more or less heavy or moveable,
but also differently shaped. Whoever has observed the phenomena which
Newton calls _the access of easy reflection_, and of _easy transmission
of light_; and on the effects of double refraction of rock and Iceland
chrystal, must have perceived that the atoms of light have many sides,
many different surfaces, which, according as they present themselves,
constantly produce different effects.
This, therefore, is sufficient to demonstrate that light is neither
particular nor different from common matter; that its essence, and
its essential properties are the same; and that it differs only from
having undergone, in the point of contact, the repulsion whence its
volatility proceeds; and in the same manner as the effect of the force
of attraction extends, always decreasing as the space augments, the
effects of repulsion extend and decrease the more, but in an inverted
order, insomuch that we can apply to the expansive force all that is
known of the attractive. These are two instruments of the same nature,
or rather the same instrument, only managed in two opposite directions.
All matter will become light, for if all coherence were destroyed
it would be divided into molecules sufficiently minute, and these
molecules, being at liberty, will be determined by their mutual
attraction to rush one against the other. In the moment of the shock
the repulsive force will be exercised, the molecules will fly in all
directions with an almost infinite volatility, which, nevertheless,
is not equal to their velocity acquired in the moment of contact, for
the law of attraction being augmented as the space diminishes, it is
evident, that at the contact the space is always proportionable till
the square of the distance becomes nil, and, consequently, the velocity
acquired by virtue of the attraction must at this point become almost
infinite: and it would be perfectly so if the contact were immediate,
and, consequently, the distance between the two bodies void; but there
is nothing in nature entirely nil, and nothing truly infinite; and all
that I have observed of the _infinite_ minuteness of the atoms which
constitute light, of their _perfect_ spring, and of the _nil_ distance
in the moment of contact, must be understood only relatively. If this
metaphysical truth were doubted, a physical demonstration may be given.
It is pretty generally known that light employs seven minutes and a
half to come from the sun to the earth; supposing, therefore, the sun
at thirty-six millions of miles, light darts through this enormous
distance in that short space, that is (supposing its motion uniform),
80,000 miles in one second. But this velocity, although prodigious,
is yet far from being infinite, since it is determinable by numbers.
It will even cease to appear so prodigious, when we reflect on the
celerity of the motion of the comets to their perihelia, or even that
of the planets, and by computing that, we shall find that the velocity
of those immense masses may pretty nearly be compared to that of the
atoms of light.
So, likewise, as all matter can be converted into light by the
division and expulsion of its parts, when they feel a shock one against
another, we shall find that all the elements are convertible; and if it
have been doubted whether light, which appears to be the most simple
element, may be converted into a solid substance, it is because we have
not paid sufficient attention to every phenomena, and were infected
with the prejudice, that being essentially volatile it can never become
fixed. But it is plain that the fixity and volatility depend on the
same attractive force in the first case, and become repulsive in the
second; and from thence are we led to think that this change of matter
into light, and from light into matter, is one of the most frequent
operations of Nature.
Having shewn that impulsion depends on attraction; that the expansive
force, like the attractive, becomes negative; that light, heat, and
fire, are only modes of the common existing matter; in one word, that
there exists but one sole force, and one sole matter, ever ready to
attract or repel, according to circumstances; let us see how, with this
single spring, and this single subject, Nature can vary her works, _ad
infinitum_. In a general point of view, light, heat, and fire, only
make one object, but in a particular point of view they are three
distinct objects, which, although resembling in a great number of
properties, differ nevertheless in a few others, sufficiently essential
for us to consider them as three distinct things.
Light, and elementary fire, compose, it is said, only one and the same
thing. This may be, but as we have not yet a clear idea of elementary
fire we shall desist from pronouncing on this first point. Light and
fire, such as we are acquainted with, are two distinct substances,
differently composed. Fire is, in fact, very often luminous, but it
sometimes also exists without any appearance of light. Fire, whether
luminous or obscure, never exists without a great heat, whereas light
often burns with a noise without the least sensible heat. Light appears
to be the work of nature while fire is only the produce of the industry
of man. Light subsists of itself, and is found diffused in the immense
space of the whole universe. Fire cannot subsist without food, and
is only found in some parts of this space where man preserves it,
and in some parts of the profundity of the earth, where it is also
supported by suitable food. Light when condensed and united by the art
of man, may produce fire, but it is only as much as it lets fall on
combustible matters. Light is therefore no more, and in this single
instance, only the principle of fire and not the fire itself: even this
principle is not immediate, for it supposes the intermediate one of
heat, and which appears to appertain more than light to the essence of
fire. Now heat exists as often without light as light exists without
heat: these two principles might, therefore, appear not to bind them
necessarily together; their effects are not contemporary, since in
certain circumstances we feel heat long before light appears, and in
others we see light long before we feel any heat. Hence is not heat
a mode of being, a modification of matter, which, in fact, differs
less than all the rest from that of light, but which can be considered
apart, and still more easily conceived? It is, nevertheless, certain,
that much fewer discoveries have been made on the nature of heat than
on that of light; whether man better catches what he sees than what
he feels; whether light, presenting itself generally as a distinct
and different substance from all the rest, has appeared worthy of a
particular consideration; whereas heat, the effect of which is the most
obscure, and presents itself as a less detached and less simple object,
has not been regarded as a distinct substance but as an attribute of
light and fire.
The first thing worthy of remark, is, that the seat of heat is quite
different from that of light: the latter occupies and runs through
the void space of the universe; heat, on the contrary, is diffused
through all solid matter. The globe of the earth, and the whole matter
of which it is composed, have a considerable degree of heat. Water has
its degree of heat which it does not lose but by losing its fluidity.
The air has also heat, which we call its temperature, and which varies
much, but is never entirely lost, since its springs subsist even in
the greatest cold. Fire has also its different degrees of heat, which
appear to depend less on its own nature, than on that of the aliments
which feed it. Thus all known matter possesses warmth; and, hence, heat
is a much more general affection than that of light.
Heat penetrates every body without exception which is exposed to it,
while light passes through transparent bodies only, and is stopped and
in part repelled, by every opaque one. Heat, therefore acts in a much
more general and palpable manner than light, and although the molecules
of heat are excessively minute, since they penetrate the most compact
bodies, it seems, however, demonstrable, that they are much more gross
than those of light; for we make heat with light, by collecting it in
a great quantity. Besides, heat acting on the sense of feeling, it is
nececssary that its action be proportionate to the grossness of this
sense, the same as the delicacy of the organs of sight appears to be to
the extreme fineness of the parts of light; these parts move with the
greatest velocity, and act in the instant at immense distances, whereas
those of heat have but a slow progressive motion, and only extend to
small intervals from the bodies whence they emanate.
The principle of all heat seems to be the attrition of bodies; all
friction, that is, all contrary motion between solid matters produces
heat; and if the same effect do not happen to fluids, it is because
their parts do not touch close enough to rub one against the other;
and that, having little adherence between them, their resistance to
the shock of other bodies is too weak for the heat to be produced to
a sensible degree; but we often see light produced by an attrition of
a fluid, without feeling any heat. All bodies whether great or little
become heated as soon as they meet in a contrary direction; heat is,
therefore, produced by the motion of all palpable matter; while the
production of light, which is also made by motion, but in a contrary
direction, supposes also the division of matter into very minute parts:
and as this operation of Nature is the same with respect to both, we
must conclude, that the atoms of light are solid of themselves, and are
hot at the moment of their birth. But we cannot be equally certain,
that they preserve their heat in the same degree as their light, nor
that they cease to be hot before they cease to be luminous.
It is well known, that heat grows less, or cold becomes greater, the
higher we ascend on the mountains. It is true that the heat which
proceeds from the terrestrial globe, is of course sensibly less on
those advanced points, than it is on the plains; but this cause is not
proportionable to the effect; the action of heat, which emanates from
the terrestrial globe, not being able to diminish but by the square of
the distance, it does not appear that at the height of half a mile,
which is only the three thousandth part of the semi-diameter of the
globe, whose centre must be taken for the focus of heat, that this
difference, which in this supposition is only a unit and nine millions,
can produce a diminution of heat nearly so considerable; for the
thermometer lowers at that height, at all times of the year, to the
freezing point. It is not probable, that this great difference of heat
simply proceeds from the difference of the earth; and of that we must
be fully convinced, if we consider, that at the mouth of the volcanos,
where the earth is hotter than in any other part on the surface of the
globe, the air is nearly as cold as on other mountains of the same
height.
It may then be supposed that the atoms of light, though very hot at the
moment of quitting the sun, are greatly cooled during the seven minutes
and a half in which they pass from that body to the earth; and this
in fact would be the case if they were detached; but, as they almost
immediately succeed each other, and are the more confined as they are
nearer the place of their origin, the heat lost by each atom falls on
the neighbouring ones; and this reciprocal communication supports the
general heat of light a longer time; and as their constant direction is
in divergent rays, their distance from each other increases according
to the space they run over; and as the heat which flies from each
atom, as a centre, diminishes also in the same ratio, it follows, that
the light of the solar rays, decreasing in an inverted ratio from the
square of the distance, that of their heat decreases in an inverted
ratio of the square of the same distance.
Taking therefore the semi-diameter of the sun for a unit, and supposing
the action of light to be as 1000 to the distance of a demi-diameter
of the surface of this planet, it will not be more than as 1000/4
to the distance of two demi-diameters; as 1000/9 to that of three
demi-diameters, as 1000/16 to the distance of four demi-diameters; and
finally, when it arrives at us, who are distant from the sun thirty-six
millions of leagues, that is about two hundred and twenty-four of its
demi-diameters, the action of light will be no more than as 1000/50625,
that is, more than 50,000 times weaker than at its issuing from the
sun; and the heat of each atom of light being also supposed 1000 at its
issuing from the sun, will not be more than as 1000/16 1000/81 1000/256
to the successive of 1, 2, 3, demi-diameters, and, when arrived at
us, as 1000/2562890625 that is, more than two thousand five hundred
millions of times weaker than at issuing from the sun.
If even this diminution of the heat of light should not be admitted
by reason of the squared square of the distance to the sun, it will
still be evident that heat, in its propagation, diminishes more than
light. If we excite a very strong heat, by kindling a large fire, we
shall only feel it at a moderate distance but we shall see the light
at a very great one. If we bring our hands by degrees nearer and nearer
a body excessively hot, we shall perceive that the heat increases
much more in proportion than as the space diminishes; for we may warm
ourselves with pleasure at a distance which differs only by a few
inches from that at which we should be burnt. Every thing, therefore,
appears to indicate, that heat diminishes in a greater ratio than
light, in proportion as both are removed from the focus whence they
issued.
This might lead us to imagine, that the atoms of light would be very
cold when they came to the surface of our atmosphere; but that by
traversing the great extent of this transparent mass, they receive a
new heat by friction. The infinite velocity with which the particles
of light rub against those of the air, must produce a heat so much the
stronger as the friction is more multiplied: and it is, probably, for
this reason, that the heat of the solar rays is found much stronger in
the lower parts of the atmosphere, and that the coldness of the air
appears to augment as we are elevated. Perhaps, likewise, as light
receives heat only by uniting, a great number of atoms of light is
required to constitute a single atom of heat, and this may be the
cause why the feeble light of the moon, although in the atmosphere,
like that of the sun, does not receive any sensible degree of heat.
If, as M. Bouguer says, the intensity of the light of the sun to
the surface of the earth is 300,000 times stronger than that of the
moon, the latter must be almost insensible, even by uniting it in the
focus of the most powerful burning glasses, which cannot condense it
more than 2000 times; subtracting the half of which for the loss by
reflexion or refraction, there remains only a 300dth part intensity to
the focus of the glass.
Thus, we must not infer that light can exist without any heat, but
only that the degrees of this heat are very different, according to
different circumstances, and always insensible when light is very weak.
Heat, on the contrary, seems to exist habitually, and even to cause
itself to be strongly felt without light; for in general it is only
when it becomes excessive, that light accompanies it. But the very
essential difference between these two modifications of matter is,
that heat, which penetrates all bodies, does not appear to fix in any
one, whereas light incorporates and extinguishes in all those which do
not reflect, or permit it to pass freely; heat bodies of all kinds
to any degree, in a very short time they will lose the acquired heat,
and return to the general temperature. If we receive light on black
or white bodies, rude or polished, it will easily be perceived, that
some admit, and others repel it; and that instead of being affected in
a uniform manner as they are by heat, they are only so relatively to
their nature, colour, and polish. Black will absorb more light than
white, and the rough more than the smooth. Light once absorbed remains
fixed in the body which received it, nor quits it like heat; whence
we must conclude, that atoms of light may become constituent parts of
bodies by uniting with the matter which composes them; whereas heat
not fixing at all, seems to prevent the union of every part of matter,
and only acts to keep them separate. Nevertheless, there are instances
where heat remains fixed in bodies, and others where the light they
have absorbed re-appears, and goes out like heat.
After all there appear to be two kinds of heat, the one luminous, of
which the sun is the focus; the other obscure, of which the grand
reservoir is the terrestrial globe. Our body, as making part of the
globe, participates of this obscure heat; and it is for this reason,
that it is still obscure to us, because we do not perceive it by any
one of our senses. It is with respect to this heat of the globe, as
with its motion, we are subject to and participate thereof without
feeling or doubting of it: from hence it happened that physicians at
first carried all their views and enquiries on the heat of the sun,
without suspecting that it makes but a very small part of what we
really feel; but having made instruments to discover the difference of
the immediate heat of the rays of the sun, they with astonishment found
that the heat of them was sixty-six times stronger in summer than in
winter, notwithstanding the strongest heat of our summer differs only
a seventh from the strongest cold of our winter; from whence they have
concluded, that, independent of the heat we receive from the sun, there
emanates another, even from this terrestrial globe, which is much more
considerable; insomuch, that it is at present demonstrable, that this
heat, which escapes from the bowels of the earth, is in our climate at
least twenty-nine times in summer, and four hundred times in winter,
stronger than the heat which comes to us from the sun.
This strong heat which resides in the interior part of the globe, and
which, without ceasing to emanate externally, must, like an element,
enter into the combination of all the other elements. If the sun is
the parent of Nature, the heat of the earth must be the mother; they
both unite to produce, support, and animate organized beings, and to
assimilate and compose inanimate substances. This internal heat of the
globe, which tends always from the centre to the circumference, is, in
my opinion, a great agent in nature. We can scarcely doubt but it is
the principal influence on the perpendicularity of the trunks of trees,
on the phenomena of electricity, on the effects of magnetism, &c. But
as I do not pretend to make a physical treatise here, I shall confine
myself to the effects of this heat on the other elements. It is alone
sufficient to maintain the rarefaction of the air to the degree that
we breathe in: it is more than sufficient to keep water in its state
of fluidity, for we have lowered the thermometers to the depth of 120
fathoms, and have found the temperature of the water was there nearly
the same as at the like depth in the earth, namely, ten degrees two
thirds. We must not, therefore, be surprized, especially as salt acts
as a prevention, that the sea in general does not freeze, that fresh
water freezes but to a certain thickness, and that the water at bottom
always remains liquid, even in the most intense frosts.
But of all the elements the earth is that on which this internal
heat must necessarily have produced, and still produces the greatest
effects. This heat originally was doubtless much greater than it is
at present; therefore we must refer to it, as to the first cause, all
the sublimations, precipitations, aggregations, and separations, which
have been, and still continue to be made in the internal part of the
globe, especially in the external layer which we have penetrated, and
the matter of which has been removed by the convulsions of Nature, or
by the hands of man. The whole mass of the globe having been melted, or
liquefied, by fire, the internal is only a concrete or discreet glass,
whose simple substance cannot receive any alteration by heat alone;
there is, therefore, only an upper and superficial layer, which being
exposed to the action of external causes united to that of the internal
heat, will have undergone all the modifications, differences, and
forms, in one word, of Mineral Substances, which their combined actions
were enabled to produce.
Fire, which at first sight appears to be only a compound of heat and
light, might also be a modification of the matter, though it does
not essentially differ from either, and still less from both taken
together. Fire never exists without heat, but it can exist without
light. Heat alone, deprived of all appearance of light, can produce the
same effects as the most violent fire; so can also light, when it is
united. Light seems to carry a substance in itself which has no need
of fuel; but fire cannot subsist without absorbing the air, and it
becomes more violent in proportion to the quantity it absorbs; whereas
light, concentrated and received into a vessel exhausted of air, acts
as fire in air; and heat, confined and retained in a narrow space,
subsists and even augments with a very small quantity of food. The most
general difference between fire, heat, and light, appears, therefore,
to consist in the quantity, and perhaps quality, of their food.
Air is the first food of fire; combustible matters are only the second.
It has been demonstrated, by experiments, that a little spark of
fire, placed in a vessel well closed, in a short time absorbs a great
quantity of air, and becomes extinguished as soon as the quantity or
quality, of this food becomes deficient. By other experiments it is
proved, that the most combustible matters will not consume in vessels
well closed, although exposed to the action of the greatest fire. Air
is, therefore, the first and true food of fire, and combustible matters
would not be able to supply it without the assistance and mediation of
this element.
We have observed that heat is the cause of all fluidity, and we find,
by comparing some fluids together, that more heat is requisite to keep
iron in fusion than gold; and more to keep gold than tin; much less
is necessary for wax, for water less than that, and still less for
spirits of wine, and a mere trifle is sufficient for mercury, since
the latter goes 187 degrees below what water can without losing its
fluidity; mercury, therefore, is the most fluid of all matter, air
excepted. Now this superior fluidity in air indicates the least degree
of adherence possible between its constituting parts, and supposes them
of such a figure as only to be touched at one point. It may be also
imagined, that, being endowed with so little apparent energy and mutual
attraction, they are, for that reason, less massive, and more light,
than those of every other body; but that conclusion appears unfounded,
from the comparison of mercury, the next fluid body, but of which the
constituting parts appear to be more massive and heavy than those of
any other matter, excepting gold. The greater or lesser fluidity, does
not, therefore, indicate that the parts of the fluid are more or less
weighty, but only that their adherence is so much the less, and their
separation so much the easier.
Air, therefore, of all known matter, is that which heat divides the
easiest, and is very near the nature of fire, whose property consists
in the expansive motions of its parts; and it is from this similarity
that air so strongly augments the activity of fire, to which it is the
most powerful assistant, and the most intimate and necessary food.
Even combustible matters will not keep it alive if deprived of air,
for under this privation the most intense fire will not burn; but a
single spark of air is sufficient to kindle them, and in proportion as
it is supplied with that element the fire becomes strong, extended, and
devouring.
Artificial phosphorus, and gunpowder, seem, at first, to be an
exception, for they have no need of the assistance of renewed air to
inflame and wholly consume them: their combustion may be performed in
the closest vessels, but that is because those matters, which are also
the most combustible, contain the necessary quantity of air in their
substance, therefore they have no need of the assistance of foreign
air.
This seems to indicate that the most essential difference between
combustible matters and those which are not so, consists in the latter
containing only a few or none of the light, ethereal, and oily matters
susceptible of an expansive motion, or, at least, if they contain them,
that they are fixed, so that they cannot exercise their volatility
whenever the force of the fire is not strong enough to surmount the
force of adhesion which retains them united to the fixed parts of
matter. It may be said that this induction is confirmed by a number of
observations well known to chemists; but what appears to be less so,
and which, nevertheless, is a necessary consequence of it, is, that
all matter may become volatile when the expansive force of the fire
can be rendered superior to the attractive force which holds the parts
of matter united; for though to produce a fire sufficiently strong it
may require better constructed mirrors than any at present known, yet
we are certain that fixity is only a relative quality, and that there
is no matter absolutely so, since heat dilates the most fixed bodies.
Now is not this dilation the index of a beginning separation, that may
be augmented with a degree of heat to fusion, and with a still greater
heat to volatilisation?
Combustion supposes something more than volatilisation; it is not
sufficient that the parts of matter be sufficiently separated to be
carried off by those of heat; they must also be of an analogous nature
to fire; without that, mercury, being the most fluid next to air, would
also be the most combustible, whereas experience demonstrates, that
though very volatile it is not combustible. Matter is, in general,
composed of four principal substances, called _elements_, that is,
earth, water, air, and fire. Those in which earth and water predominate
will be fixed, and will only become volatile by the action of heat;
and those which contain most air and fire will be the only real
combustibles. The great difficulty here is clearly to conceive how air
and fire, both so volatile, can fix and become constituent parts of all
bodies.
Fire, by absorbing air, destroys the spring. Now there are but two
methods of destroying a spring, either by compressing it till it
breaks, or extending it till it loses its effect. It is plain that
fire cannot destroy air by compression, since the least degree of heat
rarefies it; on the contrary, by a very strong heat the rarefaction of
the air will be so great that it will occupy a space thirteen times
more extended than that of its general volume; and by this means the
spring becomes weakened, and it is in this state that it can become
fixed, and unite with other bodies.
Light, which falls on bodies, is not merely reflected, but remains in
quantities on the small thickness of the surface which it strikes;
consequently it loses its motion, extends, is fixed, and becomes a
constituent part of all that it penetrates. Let us add this light,
transformed and fixed in bodies, to the above air, and to both, the
constant and actual heat of the terrestrial globe, whose sum is much
greater than that which comes from the sun, and then it will appear to
be not only one of the greatest springs of the mechanism of Nature, but
an element with which the whole matter of the globe is penetrated.
If we consider more particularly the nature of combustible matters,
we shall find, that they all proceed originally from vegetables and
animals; in a word, from bodies placed on the surface of the globe,
which the sun enlightens, heats, and vivifies. Wood, bitumen, resins,
coals, fat and oil, by expression, wax, and suet, are substances
proceeding immediately from animals and vegetables. Turf, fossil, coal,
amber, liquid, or concrete bitumens, are the productions of their
mixture, and their decomposition, whose ulterior waste forms sulphurs,
and the combustible parts of iron, tin, pyrites, and every inflammable
mineral. I know, that this last assertion will be rejected by those
who have studied nature only by the mode of chemistry; but I must
request them to consider, that their method is not that of nature, and
that it cannot even approach it without banishing all those precarious
principles, those fictitious beings which they play upon, without being
acquainted with them.
But, without pressing longer on those general considerations, let
us pursue in a more direct and particular manner the examination of
fire and its effects. The action of fire depends much on the manner
in which it is applied; and the effects of its motion, on similar
substances, will appear different according to the mode in which it
is administered. I conceive that fire should be considered in three
different states, first relative to its velocity; secondly, as to its
volume; and thirdly, as to its mass. Under each of these points of
view, this element, so simple, and so uniform to all appearance, will
appear extremely different. The velocity of fire is augmented without
the apparent volume being increased, every time that in a given space
and filled with combustible matters, its action and expansion is
pressed by augmenting the velocity of the air by bellows, caverns,
ventilators, aspirative tubes, &c. all of which accelerate more or less
the rapidity of the air directed on the fire. The action of fire is
augmented by its volume, when a great quantity of combustible matters
is accumulated, and the heat and fire are driven into the reverberatory
furnaces, which comprehend those of our glass, porcelain, and pottery
manufactories, and all those wherein metals and minerals are melted,
iron excepted. Fire acts here by its volume, and has only its own
velocity, since the rapidity is not augmented by the bellows, or other
instruments which carry air to the fire.
There are many modes of augmenting the action of fire by its velocity
or volume; but there is only one way of augmenting its mass; namely,
by uniting it in the focus of a burning glass. When we receive on the
refracting, or reflecting mirror, the rays of the sun, or even those of
a well-kindled fire, we unite them in so much the less space, as the
mirror is longer, and the focus shorter; for example, by a mirror of
four feet diameter, and one inch focus, it is clear, that the quantity
of light, or fire, which falls on the four-feet mirror, will be united
in the space of one inch, that is, it will be 2304 times denser than
it was, if all the incident matter arrived to this focus without any
loss, and when even the loss is two thirds or three fourths, the mass
of fire concentrated in the focus of this mirror, will always be six
or seven hundred times denser than on the surface. In this, as in all
other cases, the mass goes by the contraction of the volume; and the
fire which we thus augment the density of, has all the properties of a
mass of matter; for, independently of the action of heat, by which it
penetrates bodies, it impels and displaces them as a solid moving body
which strikes another would do.
Each of these modes of administering fire, and increasing either the
velocity, volume, or mass, often produce very different effects on the
same substances; insomuch, that no reliance is to be placed on any
thing that cannot be worked at the same time, or successively, by all
three. In the like manner, as I divide into three general proceedings
the administration of this element, I divide every matter that can
be submitted to its action into three classes. Passing over for the
present those which are purely combustible, and which immediately
proceed from animals and vegetables; we proceed to minerals, in the
first class of which we reckon those mineral matters, which this
action, continued for a long time, renders lighter, as iron; in the
second, such as it renders heavier, as lead; and in the third class,
are those matters on which, as gold, this action of fire does not
appear to produce any sensible effect, since it does not at all alter
their weight. All existing matters, that is, all substances simple and
compounded, will necessarily be comprized under one of these three
classes; and experiments on them by the three proceedings, which are
not difficult to be made, and only require exactness and time, might
develope many useful discoveries, and prove very necessary to build
on real principles the theory of chemistry, which has hitherto been
carried on by a precarious nomenclatura, and on words the more vague as
they are the more general.
Fire is the lightest of all bodies, notwithstanding which it has
weight, and it may be demonstrated, that even in a small volume it is
really heavy, as it obeys, like all other matters, the general law of
gravity, and consequently must have connections or affinities with
other bodies. All matters it renders more weighty will be those with
which it has the greatest affinity. One of the effects of this affinity
in the matters is to retain the substance even of fire, with which it
is incorporated, and this incorporation supposes that fire not only
loses its heat and elasticity, but even all its motion, since it fixes
itself in these bodies, and becomes a constituent part. From which it
may be imagined that there is fire under a fixed and concrete form in
almost every body.
It is evident, that all matters, whose weight increases by the
action of fire, are endowed with an attractive force superior to the
expansive, the fiery particles of which are animated; this being
extinguished the motion ceases, and the elastic and fugitive particles
become fixed, and take a concrete form. Thus matters, whose weight is
increased by fire, as tin, lead, &c. are substances which, by their
affinity with fire, attract and incorporate. All matters, on the
contrary, which, like iron, copper, &c. become lighter in proportion as
they are calcined, are substances whose attractive forces, relative to
the igneous particles, is less than the expansive force of fire; and
hence the fire, instead of fixing in these matters, carries off and
drives away the least adherent parts which cannot resist its impulsion.
Those which, like gold, platina, silver, &c. neither lose nor acquire
by the application of fire, are substances which, having no affinity
with fire, and not being able to unite, cannot, consequently, either
retain or accompany it when it is carried off. It is evident that the
matters of the two first classes have a certain degree of affinity with
fire, since those of the second class are loaded with fire, which they
retain; and the fire loads itself with those of the first class, which
it carries off; whereas the matters of the third class, to which it
neither lends nor borrows, have not any affinity or attraction with it,
but are indifferent to its action, which can neither unnaturalize nor
even change them.
This division of every matter into three classes, relative to the
action of fire, does not exclude the more particular and less absolute
division of all matters into two other classes, hitherto regarded as
relative to their own nature, which is said to be always vitrifiable,
or calcareous. Our new division is only a more elevated point of view,
under which we must consider them, to endeavour to deduce therefrom
even the agent that is used by the relations fire can have with every
substance to which it is applied.
We might say, with naturalists, that all is vitrifiable in Nature,
excepting that which is calcareous: that quartz, chrystals, precious
stones, flints, granites, porphyries, agates, gypsums, clays, lava,
pumice stone, with all metals and other minerals, are vitrifiable
either by the fire of our furnaces, or that of mirrors; whereas marble,
alabaster, stones, chalk, marl, and other substances which proceed from
the residue of shells and madrepores, cannot be reduced into fusion
by these means. Nevertheless I am persuaded, that if the power of our
furnaces and mirrors were further increased, we should be enabled to
put these calcareous matters in fusion; since there are a multiplicity
of reasons to conclude, that at the bottom their substance is the same,
and that glass is the common basis of all terrestrial matter.
By my own experiments I have found, that the most powerful glass
furnaces is only a weak fire, compared with that of bellows furnaces;
and that fire produced in the focus of a good mirror, is stronger than
that of the most glowing fire of a furnace. I have kept iron ore for
thirty-six hours in the hottest part of the glass furnace of Rouelle,
in Burgundy, without its being melted, agglutinated, or even in any
manner changed; whereas, in less than twelve hours this ore runs in a
forge furnace. I have also melted, or volatilized, by a mirror many
matters which neither the fire, nor reverberatory furnace, nor the
most powerful bellows furnace could cause to run.
It is commonly supposed, that flame is the hottest part of fire, yet
nothing is more erroneous than this opinion; the contrary may be
demonstrated by the most simple and familiar experiments. Offer to a
straw fire, or even to the flame of a lighted faggot, a cloth to dry or
heat, and treble the time will be required to what would be necessary
if presented to a brasier without flame. Newton very accurately defines
flame to be a burning smoke, and this smoke, or vapour, has never the
same quantity or intensity of heat as the combustible body from which
it escapes. By being carried upwards and extending, it has the property
of communicating fire, and carrying it further than the heat of the
brasier, which alone might not be sufficient to communicate it when
even very near.
The communication of fire merits a particular attention. I found, after
repeated reflections that besides the assistance of facts which appear
to have a relation to it, that experiments were necessary to understand
the manner in which this operation of Nature is made. Let us receive
two or three thousand weight of iron in a mould at its issuing from
the furnace; this metal in a short time loses its incandescence, and
ceases from its redness, according to the thickness of the ingot. If at
the moment its redness leaves it, it is drawn from the mold, the under
parts will be still red, but this colour will fly off. Now so long as
the redness subsists, we can light combustible matters by applying them
to the ingot; but as soon as it has lost its incandescent state, there
are numbers of matters which it will not set fire to, although the heat
which it diffuses is, perhaps a hundred times stronger than that of a
straw fire, which would inflame them. This made me think that flame
being necessary to the communication of fire, there is therefore a
flame in all incandescence. The red colour seems, in fact, to indicate
it; and indeed I am convinced, that combustible, and even the most
fixed matters, such as gold and silver, when in an incandescent state,
are surrounded with a dense flame which extends only to a very short
distance, and which is attached to their surface; and I can easily
conceive, that when flame becomes dense to a certain degree, it ceases
from obeying the fluctuation of the air. This white or red body, which
issues from all bodies in incandescence, and which strikes our eyes,
is the evaporation of this dense flame which surrounds the body by
renewing itself incessantly on its surface; and even the light of the
sun, which emits such an amazing brightness, I presume to be only an
evaporation of the dense state that constantly plays on its surface;
and which we must regard as a true flame, more pure and dense than any
proceeding from our combustible matters.
It is, therefore, by light that fire communicates, and heat alone
cannot produce the same effect as when it becomes very strong to be
luminous. Even water, that destructive element to fire, by which alone
we can prevent its progress, nevertheless communicates when in a
well-closed vessel, such as Papin's digester, where it is penetrated
with a sufficient quantity of fire to render it luminous, and capable
of melting lead and tin, whereas when it is only boiling, far from
communicating fire, it extinguishes it immediately. It is true, that
heat alone is sufficient to prepare and dispose combustible bodies for
inflammation, by driving off the humid parts from bodies; and what is
very remarkable, this heat, which dilates all bodies, does not desist
from hardening them by drying. I have an hundred times discovered, by
examining the stones of my great furnaces, especially the calcareous,
they increased in hardness in proportion to the time they had undergone
the heat, and they also at the same time became specifically heavier.
From this circumstance, I think an induction may be drawn, which
would prove, and fully confirm, that heat, although in appearance
always fugitive and never stable in the bodies which it penetrates,
nevertheless deposits in a positive manner many parts which fixes there
even in greater quantities than the aqueous and other parts which it
has driven off. But what appears very difficult to be reconciled,
this same calcareous stone, which becomes specifically heavier by the
action of a moderate heat a long time continued, becomes near a half
lighter, when submitted to a fire sufficient for its calcination, and,
at the same time, not only loses all the hardness it had acquired by
the action of heat, but even the natural adherence of its constituting
parts.
Calcination generally received, is, with respect to fixed and
incombustible bodies, what combustion is to volatile and inflammable.
Calcination, like combustion, needs the assistance of air; it operates
so much the quicker, as it is furnished with a greater quantity of that
element, without which the fiercest fire cannot calcine nor inflame
any thing, except such matters as contain in themselves all the air
necessary for those purposes. This necessity for the concurrence of
air in calcination, as in combustion, indicates, that there are more
things common between them than has been suspected. The application of
fire is the principle of both; that of air is the second cause, and
almost as necessary as the first; but these two causes are equally
combined, according as they act in more or less time, and with more or
less power on different substances.
Combustion operates almost instantaneously; calcination is sometimes
so long, as to be thought impossible; for in proportion as matters
are more incombustible, the calcination is there more slowly made;
and when the constituent parts of a substance, such as gold, are not
only incombustible, but appear so fixed as not to be volatilized,
calcination produces no effect. They must both, therefore, be
considered as effects of the same cause, whose two extremes are
delineated to us by phosphorus, which is the most inflammable of all
bodies, and by gold, which is the most fixed and least combustible.
All substances comprized between these two extremes, will be more or
less subjected to the effects of combustion and calcination, according
as they approach either of them; insomuch, that in the middle points
there will be found substances that endure an almost equal degree
of both; from which we may conclude, that all calcination is always
accopmanied with a little combustion, and all combustion with a little
calcination. Cinders and other residue of the most combustible matters,
demonstrate that fire has calcined all the parts it has not burned,
and consequently, a little calcination is found here with combustion.
The small flame which rises from most matters, that are calcined,
demonstrates also that a slight combustion is made. Thus, we must not
separate these two effects, if we would find out the results of the
action of fire on the different substances to which it is applied.
But it may be said, that combustion always diminishes the volume or
mass, on account of the quantity of matter it consumes; and that, on
the contrary, calcination increases the weight of many substances.
Ought we then to consider these two effects whose results are so
contrary, as effects of the same nature? Such an objection appears
well-founded, and deserves an answer, especially as this is the most
difficult point of the question. For that purpose let us consider a
matter in which we shall suppose one half to be fixed parts, and the
other volatile or combustible. By the application of fire to this,
all the volatile or combustible parts will be raised up or burnt, and
consequently separated from the whole mass; from hence this mass or
quantity of matter will be found diminished one half, as we see it
in calcareous stones, which lose near half their weight in the fire.
But if we continue to apply the fire for a very long time to the other
half, composed of fixed parts, all combustion and volatilization
being ceased, that matter, instead of continuing to lose its mass,
must increase at the expense of the air and fire with which it is
penetrated; and those are matters already calcined, and prepared
by Nature to the degree where combustion ceases, and consequently
susceptible of increasing the weight from the first moment of the
application. We have seen, that light extinguishes on the surface of
all bodies which do not reflect; and that heat, by long residence,
fixes partly in the matters which it penetrates; we know also that
air is necessary for calcination, or combustion, and the more so for
calcination as having more fixity in the external parts of bodies, and
becomes a constituent part: hence, it is natural to imagine, that this
augmentation of weight proceeds only from the addition of the particles
of light, heat, and air, which are at length fixed and united to one
matter, against which they have made so many efforts, without being
able either to raise or burn them. This appears clearly to be the
fact, for if we afterwards present a combustible substance to them they
will quit the fixed matter, to which they were only attached through
force, retake their natural motion, elasticity, and volatility, and
all depart with it; from hence, metal, or calcinized matter, to which
these volatile parts has been rendered, retakes its pristine form,
and its weight is found diminished by the whole quantity of fiery
and airy particles which were fixed in it, and which had been just
raised by this new combustion. All this is performed by the sole law
of affinities; and there seems to be no more difficulty to conceive
how the lime of a metal is reduced, than to understand how it is
precipitated in dissolution; the cause is the same, and the effects are
similar. A metal dissolved by an acid, will precipitate when to this
acid another substance is offered with which it has more affinity than
metal, the acid then quits it and falls to the bottom. So, likewise,
this metal calcines, that is, loaded with parts of air, heat, and
fire, which being fixed, keeps it under the form of a lime, and will
precipitate, or be reduced, when presented to this fire and fixed air,
from the combustible matters with which they have more affinity than
with the metal; the latter will retake its first form as soon as it is
disembarrassed from this superfluous air and fire, at the expence of
the combustible matters offered to it, and the volatile parts it had
lost.
I think I have now demonstrated, that all the little laws of chemical
affinities, which appeared so variable and different, are no other
than the general laws of attraction, common to all matter; that this
great law, always constant and the same, appeared only to vary in
its expression, which cannot be the same when the figure of bodies
enters, like an element, into their distance. With this new key we
can unlock the most profound secrets of Nature; we can attain the
knowledge of the figure of the primitive parts of different substances;
assign the laws and degrees of their affinities; determine the forms
which they take by re-uniting, &c. I think also I have made it appear
that impulsion depends on attraction; and that, although it may be
considered as a different force, it is, notwithstanding, a particular
effect of this sole and general one. I have shewn the communication
of motion to be impossible without a spring, whence I have concluded,
that all bodies in Nature are more or less elastic, and that there
is not one perfectly hard; that is, entirely deprived of a spring,
since all are susceptible of receiving motion. I have endeavoured to
shew how this sole force may change direction, and attraction become
repulsion; and from these grand principles, which are all founded on
rational mechanics, I have sought to deduce the principal operations
of Nature, such as the production of light, heat, and fire, and their
action on different substances; this last object which interests us
the most is a vast field, but of which I can only cultivate a little
spot, yet I presume I may render some assistance, by putting into
more capable and laborious hands the instruments I made use of. These
instruments were the three modes of making use of fire, that is, by its
velocity, volume, and mass; by applying it concurrently to the three
classes of substances, which either lose, gain, or are not affected
by the application of fire. The experiments which I had made on the
refrigeration of bodies, on the real weight of fire, on the nature of
flame, on the progress of heat, or its communication, its diperdition,
its concentration, or its violent action without flame, &c. are also
so many instruments which will spare much labour to those who choose
to avail themselves of them, and will produce an ample harvest of
knowledge.
OF AIR, WATER, AND EARTH.
By our former observations it appears that air is the necessary and
first food of fire, which can neither subsist nor propagate but by what
it assimilates, consumes, or carries off, of that element, whereas
of all material substances, air is that which seems to exist the
most independently of the aid or presence of fire; for although it
habitually has nearly the same heat as other matters on the surface
of the earth, it can do without it and requires infinitely less than
any of the rest to support its fluidity, since the most excessive cold
cannot deprive it of that. The strongest condensations are not capable
of breaking its spring; the active fire, in combustible matters, is the
only agent which can alter its nature by rarefying and extending its
spring to the point of rendering it ineffectual, and thus destroying
its elasticity. In this state, and in all the links which precede, the
air is capable of re-assuming its elasticity, in proportion as the
vapours of combustible matters evaporate and separate from it. But if
the spring have been totally weakened and extended that it cannot
re-instate itself, from having lost all its elastic power, the air,
volatile as it might before have been, becomes a fixed substance which
incorporates with the other substances, and forms a constituent part of
all those to which it unites by contact. Under this new form it can no
longer forsake the fire, except to unite, like fixed matter, to other
fixed matters; and if there remain some parts inseparable from fire,
they then make a portion of that element serve it for a base, and are
deposited with it in the substance they heat and penetrate together.
This effect is manifested in all calcinations, and is the more sensible
as the heat is longer; but combustion demands only a small time to
completely effectuate the same. If we wish to hasten calcination the
use of bellows may be necessary, not so much to augment the heat of the
fire as to establish a current of air on the surface of the matters;
yet it is not requisite for the fire to be very fierce to deprive air
of its elasticity, for a very moderate heat, when constantly applied
on a small quantity, is sufficient to destroy the spring; and for this
air, without spring, to fix itself afterwards in bodies, there is only
a little more or less time required, according to the affinity it may
have under this new form, with the matters to which it unites. The
heat of the body of animals, and even vegetables, is sufficiently
powerful to produce this effect. The degrees of heat are different in
different kinds of animals: birds are the hottest, from which we pass
successively to quadrupeds, man, cetaceous animals, reptiles, fish,
insects, and, lastly, to vegetables, whose heat is so trifling as to
have made some naturalists declare they had not any, although it is
very apparent, and in winter surpasses that of the atmosphere. I have
frequently observed in trees that were cut in cold weather, that their
internal part was sensibly warm, and that this heat remained for many
minutes. This heat is only moderate while the tree is young and sound,
but as soon as it grows old the heart heats by the fermentation of the
pith, which no longer circulates there with the same freedom; and as
soon as this heat begins the centre receives a red tint, which is the
first index of the perishing state of the tree, and the disorganization
of the wood. The reason naturalists have not found there was a
difference between the temperature of the air, and the heat of
vegetables is, because they have made their observations at a bad time
of the year, and not paid attention, that in the summer the heat of the
air exceeds that of the internal part of a tree; whereas in winter it
is quite the contrary. They have not remembered that the roots have
constantly the degree of heat which surrounds them, and that this heat
of the internal part of the earth is, during all winter, considerably
greater than that of the air, and the surface of the earth. They did
not consider that the motion alone of the pith, already warm, is a
necessary cause of heat, and that this motion, increasing by the action
of the sun, or by an external heat, that of vegetables must be so much
the greater as the motion of their pith is more accelerated, &c.
Here the air contributes to the animal and vital heat, as we have
seen that it does to the action of fire in combustible and calcinable
matters. Animals, which have lungs, and which consequently respire
the air, have more heat than those deprived of them; and the more
the internal surface of the lungs is extended, and ramified in a
greater number of cells, the more it presents greater superficies
to the air which the animal draws by inspiration; the more also its
blood becomes hotter, the more it communicates heat to all parts of
the body it nourishes, and this proportion takes place in all known
animals. Birds, relatively to the volume of their body, have lungs
considerably more extended than man or quadrupeds. Reptiles, even
those with a voice, as frogs, instead of lungs have a simple bladder.
Insects which have little or no blood breathe the air only by some
pipes, &c. Thus taking the degree of the temperature of the earth for
the term of comparison, I have observed that this heat being supposed
ten degrees, that of birds was nearly thirty-three, that of some
quadrupeds more than thirty-one and a half, that of man thirty and a
half, or thirty-one, whereas that of frogs is only fifteen or sixteen,
and that of fishes and insects only eleven or twelve, which is nearly
the same as that of vegetables. Thus the degree of heat in man and
animals depends on the force and extent of the lungs; these are the
bellows of the animal machine: the only difficulty is to conceive how
they carry the air on the fire which animates us, a fire whose focus
seems to be indeterminate; a fire that has not even been qualified
with this name, because it is without flame or any apparent smoke, and
its heat is only moderate and uniform. However, if we consider that
heat and fire are effects, and even elements of the same class; that
heat rarefies air, and, by extending its spring, it may render it
without effect; we may imagine, that the air drawn by our lungs being
greatly rarefied, loses its spring in the bronchiæ and little vesicles,
where it is soon destroyed by the arterial and venous blood, for these
blood-vessels are separated from the pulmonary vesicles by such thin
divisions that the air easily passes into the blood, where it produces
the same effect as upon common fire, because the heat of this blood
is more than sufficient to destroy the elasticity of the particles
of air, and to drag them under this new form into all the roads of
circulation. The fire of the animal body differs from common fire only
in more or less; the degree of heat is less, hence there is no flame,
because the vapours, which represent the smoke, have not heat enough
to inflame; every other effect is the same: the respiration of a young
animal absorbs as much air as the light of a candle, for if inclosed in
vessels of equal capacities, the animal dies in the same time as the
candle extinguishes: nothing can more evidently demonstrate that the
fire of the animal and that of the candle are not of the same class but
of the same nature, and to which the assistance of the air is equally
necessary.
Vegetables, and most insects, instead of lungs, have only aspiratory
tubes, by which they pump up the air that is necessary for them; it
passes in very sensible balls into the pith of the vine. This air
is not only pumped up by the roots but often even by the leaves,
and forms a very essential part of the food of the vegetable which
assimilates, fixes, and preserves it. Experience fully confirms all
we have advanced on this subject, and that all combustible matters
contain a considerable quantity of fixed air, as do also all animals
and vegetables, and all their parts, and the waste which proceeds
therefrom; and that the greatest number likewise include a certain
quantity of elastic air. And, notwithstanding the chimerical ideas
of some chemists, respecting phlogiston, there does not remain the
smallest doubt but that fire or light produces, with the assistance of
air, all the effects thereof.
Minerals, which like sulphur and pyrites, contain in their substance
a quantity of the ulterior waste of animals and vegetables, contain
thence combustible matters, which, like all other, contain more or less
fixed air, but always much less than the purely animal or vegetable
substances. This fixed air can be equally removed by combustion. In
animal and vegetable matters it is disengaged by simple fermentation,
which, like combustion, has always need of air for its operation.
Sulphurs and pyrites are not the only minerals Which must be looked
upon as combustible, there are many others which I shall not here
enumerate, because it is sufficient to remark, their degree of
combustion depends commonly on the quantity of sulphur which they
contain. All combustible minerals originally derive this property
either from the mixture of animal or vegetable parts which are
incorporated with them, or from the particles of light, heat, and air,
which, by the lapse of time, are fixed in their internal part. Nothing,
according to my opinion, is combustible but that which has been formed
by a gentle heat, that is, by these same elements combined in all the
substances which the sun brightens and vivifies, or in that which the
internal heat of the earth foments and unites.
The internal heat of the globe of the earth must be regarded as the
true elementary fire; it is always subsisting and constant; it enters,
like an element, into all the combinations of the other elements, and
is more than sufficient to produce the same effects on air as actual
fire on animal heat; consequently this internal heat of the earth
will destroy the elasticity of the air, and render it fixed, which
being divided into minute parts will enter into a great number of
substances, from hence they will contain articles of fixed air and
fire, which are the first principles of combustibility; but they will
be found in different quantities, according to their degree of affinity
with the substance, and this degree will greatly depend on the quantity
these substances contain of animal and vegetable parts, which appear to
be the base of all combustible matter. Most metallic minerals, and even
metals, contain great quantities of combustible parts; zinc, antimony,
iron, copper, &c. burn and produce a very brisk flame, as long as the
combustion of these inflammable parts remains, after which, if the fire
be continued, the calcination begins, during which there enters into
them new parts of air and heat, which fixes, and cannot be disengaged
but by presenting to them combustible matters, with which they have a
greater affinity than with those of the mineral, with which they are
only united by the effort of calcination. It appears to me, that the
conversion of metallic substances into dross, and their reproduction,
might be very clearly understood without applying to secondary
principles, or arbitrary hypotheses, for their explanation.
Having considered the action of fixed air in the most secret operations
of nature, let us take a view of it when it resides in bodies under
an elastic form; its effects are then as variable as the degrees of
its elasticity, and its action, though always the same, seems to give
different products in different substances. To bring this consideration
back to a general point of view, we will compare it with water and
earth, as we have already compared it with fire; the results of this
comparison between the four elements will afterwards be easily applied
to every substance, since they are all composed merely of these four
real principles.
The greatest cold that is known, cannot destroy the spring of the air,
and the least heat is sufficient for that purpose, especially when this
fluid is divided into very small particles. But it must be observed,
that between its state of fixity, and that of perfect elasticity, there
are all the links of the intermediate states, in one of which it always
resides in earth and water, and all the substances which are composed
of them; for example, water, which appears so simple a substance,
contains a certain quantity of air, which is neither fixed nor elastic,
as is plain from its congulation, ebullition, and resistance to all
compression, &c. Experimental philosophy demonstrates, that water is
incompressible, for instead of shrinking and entering into itself when
pressed, it passes through the most solid and thickest vessels; which
could not be the case if the air it contained were in a state of full
elasticity. The air contained therefore in water, is not simply mixed
therewith, but is united in a state where its spring is not sensibly
exercised; yet the spring is not entirely destroyed, for if we expose
water to congelation, the air issues from its internal part, and unites
on its surface in elastic bubbles. This alone suffices to prove, that
air is not contained in water under its common form, since being
specifically 850 times lighter, it would be forced to issue out by the
sole necessity of the preponderance of water; neither under an affixed
form, but only in a medium state, from whence it can easily retake its
spring, and separate more easily than from every other matter.
It may, with some justice, be objected that cold and heat never operate
in the same mode, and that if one of these causes gives to air its
elasticity, the other must destroy it, and I own that in general it
is so, but in this particular they produce the same effect. It is
well known that water, frozen or boiled, reabsorbs the air it had
lost as soon as it is liquefied or cooled. The degree of affinity
of air with water, depends, therefore, in a great measure, on its
temperature, which in its liquid state; is nearly the same as that of
the general heat, to the surface of the earth: the air with which it
has much affinity penetrates it as soon as it is divided into small
parts, yet the degree of elementary and general heat, weakens their
spring so as to render them ineffectual as long as the water preserves
this temperature; but if the cold penetrate, or this degree of heat
diminish, then its spring will be re-established by the cold, and the
elastic bubbles will rise to the surface of the water ready to freeze;
if, on the contrary, the temperature of the water is increased by an
external heat, the integrant parts become too much divided, they are
rendered volatile, and the air with which they are united, rises and
escapes with them. Water and air have much greater connections between
them than opposite properties, and as I am well persuaded, that all
matter is convertible, and that the elements may be transformed, I am
inclined to believe, that water can change into air when sufficiently
rarefied to raise up in vapours, for the spring of the vapour of the
water is even more powerful than the spring of the air.
Experience has taught me that the vapours of water can increase the
fire in the same manner as common air; and this air, which we may
regard as pure, is always mixed with a very great quantity of water;
but it must be remarked, as an observation of much importance, that
the proportions of the mixtures are not nearly the same in these two
elements. It may be said in general that there is much less air in
water than water in air. In considering this proportion we must refer
to the volume and mass. If we estimate the quantity of air contained in
water by the volume it will appear nil, since the volume is not in the
least increased. Thus it is not to the volume that we must relate this
proportion, it is alone to the mass, that is, to the real quantity of
matter in one and the other of these two elements that we must compare
that of their mixture, by which we shall perceive that the air is much
more _aqueous_ than the water is _aerial_, perhaps in proportion of the
mass, that is, eight hundred and fifty times. Be this estimation either
too strong or too weak we can derive this induction from it, that water
must change more easily into air than air can transform into water.
The parts of air, although susceptible of being extremely divided,
appear to be more gross than those of water, since the latter passes
through many filtres which air cannot penetrate; since the vapours of
water are only raised to a certain height in the air; and, in short,
since air seems to imbibe water like a sponge, to contain it in a
large quantity, and that the container is certainly greater than the
contained.
In the order of the conversion of the elements it appears to me, that
water is to air what air is to fire, and that all the transformations
of nature depend on them. Air, like the food of fire, assimilates with
it, and is transformed into this first element. Water, rarefied by
heat, is transformed into a kind of air capable of feeding the fire
like common air. Thus fire has a double fund of certain subsistence;
if it consume much air it can also produce much by the rarefaction of
water, and thus repair, in the mass of atmosphere, all the quantity
it destroyed, while ulteriorly it converts itself with air into fixed
matter in the terrestrial substances which it penetrates by its heat
or by its light. And so, likewise, as water is converted into air,
or into vapours, as volatile as air, by its rarefaction, it is also
converted into a solid substance by a kind of condensation. Every fluid
is rarefied by heat and condensed by cold. Water follows this common
law, and condenses as it grows cold. Let a glass tube be filled three
parts full and it will descend in proportion as the cold increases, but
some time before congelation it will ascend above the point of three
fourths of the height of the tube, and increase still more considerably
by being frozen. But if the tube be well stopped, and perfectly at
rest, the water will continue to descend, and will not freeze, although
the degree of cold be six, eight, or ten degrees below the freezing
point; congelation, therefore, presents, in an inverted manner, the
same phenomena as inflammation. A heat, however great, shut up in a
well-closed vessel, will not produce inflammation unless touched with
an inflamed matter; so, likewise, to whatsoever degree a fluid is
cooled, it will not freeze unless it touch something already frozen,
and this is what happens when the tube is shaken or uncorked; the
particles of water, which are frozen in the external air, or in the air
contained in the tube, strike the surface of the water, and communicate
their ice to it. In inflammation, the air, at first very much rarefied
by heat, loses its volume, and fixes itself suddenly. In congelation,
water, at first condensed by the cold, takes a larger volume, and fixes
itself likewise, for ice is a solid substance, lighter than water, and
would preserve its solidity if the cold continued the same; and I am
inclined to believe that we may attain the point of fixing mercury at
a less degree of cold, by sublimating it into vapours in a very cold
air; and also that water, which only owes its liquidity to heat, would
become a substance much more solid and fusible, as it would endure a
stronger and a longer time the rigour of the cold.
But without stopping upon this subject, that is, without admitting or
excluding the possibility of the conversion of the ice into infusible
matter, or fixed and solid earth, let us pass on to more extensive
views on the modes which Nature makes use of for the transformation
of water. The most powerful of all and the most evident is the animal
filter. The body of shell-animals, by feeding on the particles of
water, labours, at the same time, on the substance to the point of
unnaturalizing it. The shell is certainly a terrestrial substance,
a true stone, from which all the stones called calcareous, and many
other matters, derive their origin. This shell appears to make the
constitutive part of the animal it covers, since it is perpetuated
by generation, for it is on the small shell-animal just come into
existence as well as on those which have arrived at their full growth;
but this is no less a terrestrial substance, formed by the secretion
or exudation of the body, for it increases and thickens by rings
and layers in proportion as the animal grows; and stony matter often
exceeds fifty or sixty times the mass of the body which produces
it. Let us, for a moment, reflect on the number of the kind of
shell-animals, or rather of those animals with a stony transudation;
they, possibly, are more numerous in the sea than the insect kind
are upon earth. Let us afterwards represent their full growth, their
prodigious multiplication, and the shortness of their lives, which
we may suppose does not exceed ten years; let us then consider that
we must multiply by fifty or sixty the almost immense number of the
individuals of this class to form an idea of all the stony matter
produced in ten years; then that this block must be augmented with as
many similar blocks as there are as many times ten in all the ages from
the beginning of the world, and by this means we shall conceive, that
all our coral, rocks of calcareous stone, marble, chalk, &c. originally
proceeded alone from the cast-off coats of those little animals.
Salts, bitumen, oil, and the grease of the sea, enter little or none
into the composition of the shell; neither does the calcareous stone
contain any of those matters; this stone is, therefore, only water
transformed, joined to some little portion of vitrifiable earth, and to
a great quantity of fixed air, which may be disengaged by calcination.
This operation produces the same effect on the shells taken in the sea
as upon those drawn out of quarries; they both form lime, with only a
little difference in their quality. Lime, made with oyster or other
shells, is weaker than that made with marble or hard stone; but the
process of Nature is the same, as are the results of its operation.
Both shells and stones, lose nearly half their weight by the action
of fire in calcination; the water issues first, after which the fixed
air is disengaged, and then the fixed water, of which these stony
substances are composed, resumes its primitive nature, is elevated into
vapours, drove off and rarefied by the fire, so that there remains
only the most fixed parts of this air and water, which, perhaps, are
so strongly united in themselves, and to the small quantity of the
fixed earth of the stone, that the fire cannot separate them; the
mass, therefore, is reduced nearly a half, and would probably be still
more if submitted to a stronger fire. And what appears to me to prove
that this matter, driven out of the stone by the fire, is nothing else
than air and water, is the avidity with which calcined stone sucks up
the water given to it, and the force with which it draws water from
the atmosphere. Lime, by exposure either in air or water, in a great
measure regains the mass it had lost by calcination; the water, with
the air it contains, replaces that which the stone contained before.
Stone then retakes its first nature, for in mixing lime with the
remains of other stones, a mortar is made which hardens, and becomes a
solid substance, like those from which it is composed.
Thus, then, we see on the one hand all the calcareous matters, the
origin of which we must refer to animals; and on the other, all the
combustible matters proceeding from animal or vegetable substances;
they occupy together a great space on the earth; yet, however great
their number may be, they only form a small part of the terrestrial
globe, the principal foundation of which, and the greatest quantity
consists in one matter of the nature of glass; a matter we must look
upon as terrestrial element, to the exclusion of all other substances,
to which it serves as a base, like earth, when it forms vegetables by
the means, or remains of animals, and by the transformation of the
other elements; and it is also the ulterior term to which we can return
or reduce them all.
It appears that the animal filter converts water into stone; the
vegetable filter can also transform it, when all the circumstances are
found to be the same. The heat of vegetables and the organs of life
being less powerful than those of shell animals, the vegetables can
produce only a small quantity of stones, which are frequently found
in its fruits; but it can and does convert a great quantify of air,
and a still greater of water into its substance. It may be asserted,
without fear of contradiction, that the fixed earth it appropriates,
and which serves as a base to these two elements, does not make the
hundredth part of its mass; hence, the vegetable is almost entirely
composed of air and water, transformed into wood, or a solid substance,
which is afterwards reduced into earth by combustion and putrefaction.
The same may be said of animals; they not only fix and transform air
and water, but fire, and in a much greater quantity than vegetables.
It appears, therefore, to me, that the functions of organized bodies
are the most powerful means made use of by Nature for the conversion
of the elements. We may regard each animal, or vegetable, as a small
particular centre of heat or fire that appropriates to itself the air
and water which surround it, assimilates them to vegetate or nourish,
and live on the productions of the earth, which are themselves only
air and water previously fixed. It also appropriates to itself a small
quantity of earth, and receiving the impressions of light, the heat of
the sun and terrestrial globe, it converts into its substance all these
different elements; works, combines, unites, and opposes them, till
they have undergone the necessary form towards its support of life, and
the growth of organization, the mold of which once given, models every
matter it admits, and from inanimate renders it organized.
Water, which so readily coalesces and enters with air into organized
bodies, unites also with some solid matters, such as salts; and it is
often by their means that it enters into the composition of minerals.
Salt at first appears to be only an earth soluble in water, and of
a sharp flavour, but chemists have perfectly discovered, that it
principally consists in the union of what they term the _earthly_ and
the _aqueous principle_. The experiment of the nitrous acid, which
after combustion leaves only a small quantity of earth and water,
has caused them to think, that salt was composed only of these two
elements; yet I think it is easily to be demonstrated, that air and
fire also enter their composition; since nitre produces a great
quantity of air in combustion, and this fixed air supposes fixed fire
which disengages at the same time: besides all the explanations given
of the dissolution cannot be supported, and it would be against all
analogy, that salt should be composed only of these two elements, while
all other substances are composed of four. Hence we must not receive
literally what those great chemists Messrs. Stahl and Macquer have
said on this subject; the experiments of Mr. Hales demonstrate, that
vitriol and marine salt contain much fixed air; that nitre contains
still more, even to the eighth of its weight; and that salt of tartar
contains still more than these. It may, therefore, be asserted that air
enters as a principle into the composition of all salts; but this does
not support the idea that salt is the mediate substance between earth
and water; these two elements enter in different proportions into the
different salts or saline substances, whose variety and number are so
great, as not to be enumerated; but which, generally presented under
the denomination of acids and alkalis, shews us, that there is in
general more earth than water in the last, and more water than earth in
the first.
Nevertheless, water, although it may be intimately mixed with salts, is
neither fixed nor united there by a sufficient force to transform it
into a solid matter like calcareous stone; it resides in salt or acid
under its primitive form, and the best concentrated acid, or the most
deprived of water, which might be looked upon as liquid earth, only
owes its liquidity to the quantity of the air and fire it contains; and
it is no less certain, that they are indebted for their savour to the
same principles. An experiment which I have frequently tried, has fully
convinced me, that alkali is produced by fire. Lime made according
to the common mode, and put upon the tongue, even before slacked by
air or water, has a savour which indicates the presence of a certain
quantity of alkali. If the fire be continued, this lime by longer
calcination, becomes more poignant; and that drawn from furnaces, where
the calcination has subsisted for five or six months together, is
still more so. Now this salt was not contained in the stone before its
calcination; it augmented in proportion to the strength and continuance
of the fire; it is therefore evident, that it is the immediate product
of the fire and air, which incorporate in the substance during its
calcination, and which, by this means, are become fixed parts of it,
and from which they have driven most of the watery molecules it before
contained. This alone appeared to me sufficient to pronounce that fire
is the principal of the formation of the mineral alkali; and we may
conclude, by analogy, that other alkalis owe their formation to the
constant heat of the animal and vegetable from which they are drawn.
With respect to acids, although the demonstration of their formation
by fire and fixed air, is not so immediate as that of alkalis, yet it
does not appear less certain. We have proved, that nitre and phosphorus
draw their origin from vegetable and animal matters: that vitriol comes
from pyrites, sulphur and other combustibles. It is likewise certain
that acids, whether vitriolic, nitrous, or phosphoric, always contain a
certain quantity of alkali; we must, therefore, refer their formation
and savour to the same principle, and by reducing the varieties of
both to one of each, bring back all salts to one common origin: those
which contain most of the active principles of air and fire, will
necessarily have the most power and taste. I understand by power the
force with which salts appear animated to dissolve other substances.
Dissolution supposes fluidity, and as it never operates between two
dry or solid matters, it also supposes the principle of fluidity in
the dissolvent, that is, fire; the power of the dissolvent will be,
therefore, so much the greater, as on one part it contains more of
this active principle; and, on the other hand, its aqueous and terrene
parts will have more affinity with those of the same kind contained
in the substances to dissolve; and, as the degrees of affinity vary,
we must not be surprized at different salts varying in their action
on different substances; their active principle is the same, their
dissolving power the same; but they remain without exercise when the
substance presented repels that of the dissolvent, or has no degree of
affinity with it; but the contrary is the case when there is sufficient
force of affinity to conquer that of the coherence; that is, when the
active principles, contained in the dissolvent, under the form of air
and fire, are found more powerfully attracted by the substance to be
dissolved, than they are by the earth and water they contain. Newton
is the first who has assigned affinities as the causes of chemical
precipitation; Stahl adopted this idea and transmitted it to all the
other chemists; and it appears to be at present universally received as
a truth. But neither Newton nor Stahl saw that all these affinities,
so different in appearance, are only particular effects of the general
force of universal attraction: and, for want of this knowledge, their
theory cannot be either luminous or complete, because they were obliged
to suppose as many trivial laws of different affinities, as there were
different phenomena; instead of which there is in fact only one law
of affinity, a law which is precisely the same as that of universal
attraction.
Salts concur in many operations of Nature by the power they have of
dissolving other substances; for, although it is commonly said, that
water dissolves salt, it is easy to be perceived, that in reality,
when there is a dissolution, both are active, and may be alike called
_dissolvents_. Regarding salt as only a dissolvent, the body to be
dissolved may be either liquid or solid; and, provided the parts of the
salt be sufficiently divided to touch immediately those of the other
substances, they will act and produce all the effects of dissolution.
By this we see how much the action of salts, and the action of the
element of water which contains them, must have influence on the
composition of mineral matters. Nature may produce by this mode, all
that our arts produce by that of fire. Time only is required for salts
and water to produce on the most compact and hard substances, the most
complete division and attenuation of their parts, so as to render them
capable of uniting with all analogous substances, and to separate from
all others; but this time, which to Nature is never wanting, is, of all
things, that which is the most deficient to us: the greatest of all our
arts, therefore, is that of abridging time, that is, to effect that
in one day, which nature takes an age to perform. However vain this
pretension may appear, we must not entirely renounce it, for has not
man discovered the mode of creating fire, of applying it to his use,
and by the means of this element to suddenly dissolve those bodies by
fusion which would require a considerable period by any other means?
We must not, however, conclude that Nature really performs by the means
of water all that we do by fire. The decomposition of every substance
is only to be made by division, and the greater this division the more
the decomposition will be complete. Fire seems to divide as much as
possible those matters which it fuses; nevertheless it may be doubted
whether those which water and acids keep in dissolution are not still
more divided, and the vapours raised by heat contain matters still
further attenuated, in the bowels of the earth, then, by the means
of the heat it includes, and the water which insinuates, there is
made an infinity of sublimations; distillations, chrystallizations,
aggregations, and disjunctions, of every kind. By time all substances
may be compounded and decompounded by these means; water may divide
and attenuate the parts more than fire when it melts them, and those
attenuated parts will join in the same manner as those of fused metal
unite by cooling. Crystallization, of which the salts have given us
an idea, is never performed but when a substance, being disengaged
from every other, is much divided and sustained by a fluid, which
having little or no affinity with it, permits it to unite and form by
virtue of its force of attraction, masses of a figure nearly similar
to its primitive parts. This operation, which supposes all the above
circumstances, may be done by the intermediate aid of fire as well as
by that of water, and is often accomplished by the concurrence of both,
because all this exacts but one division of matter sufficiently great
for its primitive parts to be able to form, by uniting figured bodies
like themselves. Now fire can bring many substances to this state much
better than any other dissolvent, as observation demonstrates to us in
asbestos, and other productions of fire, whose figures are regular, and
which must be looked upon as true crystallizations. Yet this degree of
division, necessary to crystallization, is not the greatest possible,
since in this state the small parts of matter are still sufficiently
large to constitute a mass, which like other masses, is only obedient
to the sole attractive force, and the volumes of which, only touching
in points, cannot acquire the resultive force that a much greater
division might perform by a more immediate contact, and this is what
we see happen in effervescences, where at once, heat and light are
produced by the mixture of two cold liquors.
Light, heat, fire, air, water, and salts, are steps by which we descend
from the top of Nature's ladder to its base, which is fixed earth. And
these are at the same time the only principles that we must admit and
combine for the explanation of all phenomena. These principles are
real, independently of all hypotheses and all method, as are also their
conversion and transformation, which are demonstrated by experience.
It is the same with the element of earth, it can convert itself by
volatilizing and taking the form of the other elements, as those take
that of earth in fixing; it, therefore, appears quite useless to seek
for a substance of pure earth in terrestrial matters. The transparent
lustre of the diamond dazzled the sight of our chemists, when they
considered that stone as a pure elementary fire; they might have said
with as much foundation, that it is pure water, all the parts of which
are fixed to compose a solid diaphanous substance. When we would define
Nature, the large masses should alone be considered, and those elements
have been well taken notice of by even the most ancient philosophers.
The sun, atmosphere, earth, sea, &c. are all great masses on which
they established all their conclusions; and if there ever had existed
a planet of phlogiston, an atmosphere of alkali, an ocean of acid,
or a mountain of diamonds, such might have been looked upon as the
general and real principles of all bodies, but they are only particular
substances, produced, like all the rest, by the combinations of true
elements; and ideas to the contrary would never have been started but
upon the supposition that the earth was neither more simple nor less
convertible than either of the other elements.
In the great mass of solid matter, which the earth represents, the
superficial is the least pure. All the matter deposited by the sea, in
form of sediment, all stones produced by shell-animals, all substances
composed by the combinations of the waste of the animal or vegetable
kingdom, and all those which have been changed by the fires of
volcanos, or sublimated by the internal heat of the globe, are mixed
and transformed substances; and although they compose great masses
they do not clearly represent to us the element of earth. They are
vitrifiable matters, whose mass must be considered as 100,000 times
more considerable than all those other substances, which should be
regarded as the true basis of this element. It is from this common
foundation that all other substances have derived the origin of their
solidity, for all fixed matter, however much decomposed, subsides
finally into glass by the sole action of fire: it resumes its first
nature, when disengaged from the fluid, or volatile matters, which were
united with it; and this glass, or virtreous matter, which composes
the mass of our globe, represents so much the better the element of
earth, as it has neither colour, smell, taste, liquidity, nor fluidity,
qualities which all proceed from the other elements, or belong to them.
If glass be not precisely the element of earth, it is at least the most
ancient substance of it; metals are more recent, and less dignified;
and most other minerals form within our sight. Nature produces glass
only in the particular focus of its volcanos, whereas every day she
forms other substances by the combination of glass with the other
elements. If we would form to ourselves a just idea of her formation
of the globe, we must first consider her processes, which demonstrate
that it has been melted or liquefied by fire; that from this immense
heat it successively passed to its present degree; that in the first
moments, where its surface began to take consistence, inequalities
must be formed, such as we see on the surface of melted matters grown
cold: that the highest mountains, all composed of vitrifiable matters,
existed and take their date from that moment, which is also that of
the separation of the great masses of air, water, and earth; that
afterwards, during the long space of time which the diminution of the
heat of the globe to the point of present temperature supposes, there
were made in these mountains, which were the parts most exposed to
the action of external causes, an infinity of fusions, sublimations,
aggregations, and transformations, by the fire of the sun, and all the
other causes which this great heat rendered more active than they at
present are, and that consequently we must refer back to this date the
formation of metals and minerals which we find in great masses, and in
thick and continued veins. The violent fire of inflamed earth, after
having raised up and reduced into vapours all that was volatile, after
having driven off from its internal parts the matters which compose
the atmosphere and the sea, and at the same time sublimated all the
least fixed parts of the earth, raised them up and deposited them in
every void space, in all the cavities which formed on the surface in
proportion as it cooled; this, then, is the origin and the gradation
of the situation and formation of vitrifiable matters which fire has
divided, formed and sublimated.
After this first establishment (and which still subsists) of
vitrifiable matters and minerals into a great mass, which can be
attributed to the action of fire alone, water which till then formed
with air only a vast volume of vapours, began to take its present
state; it collected and covered the greatest part of the surface of
the earth, on which, finding itself agitated by a continual flux
and reflux, by the action of winds and heat, it began to act on the
works of fire: it changed, by degrees, the superficies of vitrifiable
matters; it transported the wrecks and deposited them in the form of
sediments; it nourished shell-animals, it collected their shells,
produced calcareous stones, formed hills and mountains, which becoming
afterwards dry, received in their cavities all the mineral matters they
could dissolve or contain.
To establish a general theory on the formation of Minerals, we must
begin then by distinguishing with the greatest attention, first, those
which have been produced by the primitive fire of the earth while it
was burning with heat; secondly, those which have been formed from the
waste of the first by the means of water; and thirdly, those which
in volcanos, or other subsequent conflagrations, have a second time
undergone the proof of a violent heat. These three objects are very
distinct, and comprehend all the mineral kingdom; by not losing sight
of them, and by connecting each substance, we can scarcely be deceived
in its origin, or even in the degrees of its formation. All minerals
which are found in masses, or large veins in our high mountains,
must be referred to the sublimation of the primitive fire; all those
which are found in small ramifactions, in threads or in vegetations,
have been formed only from the waste of the first hurried away by the
stillation of waters. We are evidently convinced of this, by comparing
the matter of the iron mines of Sweden with that of our own. These
are the immediate work of water, and we see them formed before our
eyes; they are not attracted by the load stone; they do not contain
any sulphur, and are found only dispersed in the earth; the rest are
all more or less sulphureous, all attracted by the load stone, which
alone supposes that they have undergone the action of fire; they are
disposed in great, hard, and solid masses: and their substance is mixed
with a quantity of asbestos, another index of the action of fire. It is
the same with other metals: their ancient foundation comes from fire,
and all their great masses have been united by its action; but all
their crystallizations, vegetations, granulations, &c. are due to the
secondary causes, in which water is the primary agent.
EXPERIMENTS ON THE PROGRESS OF HEAT IN MINERAL SUBSTANCES.
I caused ten bullets to be made of forged and beaten iron; the first,
of half-inch diameter; the second, of an inch; and soon progressively
to five inches: and as all the bullets were made of iron of the same
forge, their weights were found nearly proportionable to their volumes.
The bullet of half an inch weighed 190 grains, Paris weight; that of
an inch, 1522 grains; that of an inch and a half, 5136 grains; that of
two inches, 12173 grains; that of two inches and an half, 23781 grains;
that of three inches, 41085 grains; that of three inches and a half,
65254 grains; that of four inches, 97388 grains; that of four inches
and an half, 138179 grains; and that of five inches, 190211 grains. All
these weights were taken with very good scales, and those bullets which
were found too heavy, were filed.
While these bullets were making, the thermometer exposed to the open
air was at the freezing point, or some degrees below; but in the pit
where the bullets were suffered to cool, the thermometer was nearly ten
degrees above that point; that is to say, to the degree of temperature
of the pits of the observatory, and it is this degree which I have here
taken for that of the actual temperature of the earth. To know the
exact moment of their cooling to this actual temperature, other bullets
of the same matters, diameters, and not heated, were made use of for
comparison, and which were felt at the same time as the others. By the
immediate touch of the hand, or two hands, on the two bullets, we could
judge of the moment when they were equally cold; and as the greater or
less smoothness or roughness of bodies makes a great difference to the
touch; (a smooth body, whether hot or cold, appearing much more so than
a rough body, even of the same matter, although they are both equally
so) I took care that the cold bullets were rough, and like those
which had been heated, whose surfaces were sprinkled over with little
eminences produced by the fire.
EXPERIMENTS.
I. The bullet of half an inch was heated white in two minutes, cooled
so as to be held in the hand in 12, and to the actual temperature in 39
minutes.
II. That of an inch, heated white in five minutes and a half, cooled
so as to be held in the hand, in 35-1/2 minutes, and to the actual
temperature in one hour and 23 minutes.
III. That of an inch and an half, heated white in nine minutes,
cooled so as to be held in the hand in 58 minutes, and to the actual
temperature in two hours and 35 minutes.
IV. That of two inches heated white in 13 minutes, cooled so as to be
held in the hand in one hour 20 minutes, and to the actual temperature
in three hours 16 minutes.
V. That bullet of two inches and an half heated white in 16 minutes,
cooled so as to be held in the hand in one hour 42 minutes, and to the
actual temperature in four hours 30 minutes.
VI. That bullet of three inches heated white in 19-1/2 minutes, cooled
so as to be held in the hand in two hours seven minutes, and to the
actual temperature in five hours eight minutes.
VII. That of three inches and a half heated white in 23-1/2 minutes,
cooled so as to be held in the hand in two hours 36 minutes, and to the
actual temperature in five hours 56 minutes.
VIII. That of four inches heated white in 27 minutes and a half, cooled
so as to be held in the hand in three hours two minutes, and to the
actual temperature in six hours 55 minutes.
IX. That of four inches and a half heated white in 31 minutes, cooled
so as to be held in the hand in three hours and 25 minutes, and to the
actual temperature in seven hours 46 minutes.
X. That of five inches heated white in 34 minutes, cooled, so as to
be held in the hand, in three hours 52 minutes, and to the actual
temperature in eight hours 42 minutes.
The most constant difference that can be taken between each of the
terms which express the time of cooling, from the instant the bullets
were drawn from the fire, to that when we can touch them unhurt, is
found to be about 24 minutes, for, by supposing each term to increase
24, we shall have 12, 36, 60, 84, 108, 132, 156, 180, 204, 228 minutes.
And the continuation of the real time of these coolings are, 12,
35-1/2, 58, 80, 102, 127, 156, 182, 205, 232 minutes, which approach
the first as nearly as experiment can approach calculation.
So, likewise, the most constant difference to be found between each of
the terms of cooling to actual temperature is found to be 54 minutes,
for by supposing each term to increase 54, we shall have 39, 93, 147,
201, 255, 309, 363, 417, 471, 525 minutes, and the continuation of
the real time of this cooling is found, by the preceding experiments,
to be 39, 93, 145, 196, 248, 308, 356, 415, 466, 522 minutes, which
approaches also nearest to the first.
I made the like experiments upon the same bullets twice or thrice,
but found I could only rely on the first, because each time the
bullets were heated they lost a considerable part of their weight,
which was occasioned not only by the falling off of the parts of the
surface reduced into scoria, but also by a kind of drying, or internal
calcination, which diminishes the weight of the constituent parts,
insomuch that it appears a strong fire renders the iron specifically
lighter each time it is heated; and I have found, by subsequent
experiments, that this diminution of weight varies much, according to
the different quality of the iron. Experience has also confirmed me
in the opinion, that the duration of heat, or the time taken up in
cooling of iron, is not in a smaller, as stated in a passage of Newton,
but in a larger ratio than that of the diameter.
Now if we would enquire how long it would require for a globe as large
as the earth to cool, we should find, after the preceding experiments,
that instead of 50,000 years, which Newton assigns for the earth to
cool to the present temperature, it would take 42,964 years, 221 days,
to cool only to the point where it would cease to burn, and 86,667
years and 132 days, to cool to the present temperature.
It might only be supposed, that the refrigeration of the earth should
be considerably increased, because we imagine that refrigeration
is performed by the contact of the air, and that there is a great
difference between the time of refrigeration in the air and in
vacuo; and supposing that the earth and air cool in the same time in
vacuo, this surplus of time should be reckoned. But, in fact, this
difference of time is very inconsiderable, for though the density of
the medium, in which a body cools, makes something on the duration of
the refrigeration, yet this effect is much less than might be imagined,
since in mercury, which is eleven thousand times denser than air, it
is only requisite to plunge bodies into it about nine times as often
as is required to produce the same refrigeration in air. The principal
cause of refrigeration is not, therefore, the contact of the ambient
medium, but the expansive force which animates the parts of heat and
fire, which drives them out of the bodies wherein they reside, and
impels them directly from the centre to the circumference.
By comparing the time employed in the preceding experiments to heat
the iron globes, with that requisite to cool them, we find that they
may be heated till they become white in one sixth part and a half of
the time they take to cool, so as to be held in the hand, and about
one fifteenth and a half of that to cool to actual temperature, so
that there is a great error in the estimate which Newton made on the
heat communicated by the sun to the comet of 1680, for that comet
having been exposed to the violent heat of the sun but a short time,
could receive it only in proportion thereto, and not only in so great
a degree as that author supposes. Indeed, in the passage alluded to,
he considers the heat of red-hot iron much less than in fact it is,
and he himself states it to be, in a Memoir, entitled, _The Scale of
Heat_, published in the Philosophical Transactions of 1701, which was
many years after the publication of his _principles_. We see in that
excellent Memoir, which includes the germ of all the ideas on which
thermometers have since been constructed; that Newton, after very exact
experiments, makes the heat of boiling water to be three times greater
than that of the sun in the height of summer; that of melted tin,
six times greater; that of melted lead, eight times; that of melted
regulus, twelve times; and that of a common culinary fire, sixteen or
seventeen times; hence we may conclude, that the heat of iron, when
heated so as to become white, is still greater, since it requires a
fire continually animated by the bellows to heat it to that degree.
Newton seems to be sensible of this, for he says, that the heat of iron
in that state seems to be seven or eight times greater than that of
boiling water. This diminishes half the heat of this comet, compared to
that of hot iron.
But this diminution, which is only relative, is nothing in itself, nor
nothing in comparison with that real and very great diminution which
results from our first consideration. For the comet to have received
this heat a thousand times greater than that of red-hot iron, it must
have remained a very long time in the vicinity of the sun, whereas it
only passed very rapidly at a small distance. It was on the 8th of
December, 1680, at 6/1000 distance from the earth to the centre of the
sun; but 24 hours before, and as many after, it was at a distance six
times greater, and where the heat was consequently 36 times less.
To know then the quantity of this heat communicated to the comet by the
sun, we here find how we should make this estimation tolerably just,
and, at the same time, make the comparison with hot iron by the means
of my experiments.
We shall suppose, as a fact, that this comet took up 666 hours to
descend from the point where it then was, and which point was at an
equal distance as the earth is from the sun, consequently it received
an equal heat to what the earth receives from that luminary, and which
I here take for unity; we shall likewise suppose that the comet took
666 hours more to ascend from the lowest point of its perihelium to
this same distance; and supposing also its motion uniform, we shall
perceive, that the comet being at the lowest point of its perihelium,
that is, to 6/1000 of the distance from the earth to the sun, the heat
it received in that motion was 27,766 times greater than that the
earth receives. By giving to this motion a duration of 80 minutes,
viz. 40 for its descent, and 40 for its ascent, we shall have, at 6
distance, 27,776 heat during 80 minutes at 7 distance 20,408 heat also
during 80 minutes, and at 8 distance 15,625 heat during 80 minutes, and
thus, successively, to the distance of 1000, where the heat is one. By
summing up the quantity of heat at each distance we shall find 363,410
to be the total of the heat the comet has received from the sun, as
much in descending as in ascending, which must be multiplied by the
time, that is, by four thirds of an hour; we shall then have 484,547,
which divided by 2,000 represents the solid heat the earth received
in this time of 1332 hours, since the distance is always 1,300, and
the heat always equals one. Thus we shall have 242,547/2000 for the
heat the comet received more than the earth during the whole time of
its perihelium instead of 28,000, as Newton supposed it, because he
took only the extreme point, and paid no attention to the very small
duration of time. And this heat must still be diminished 242,547/2000,
because the comet ran, by its acceleration, as much more way in the
same as it was nearer the sun. But by neglecting this diminution, and
admitting that the comet received a heat nearly 242 times greater than
that of our summer's sun, and, consequently 17-2/7 times greater than
that of hot iron, according to Newton's estimation, or only ten minutes
greater according to this estimation; it must be supposed, that give a
heat ten times greater than that of red hot iron, it required ten times
more time; that is to say, 1332; consequently, we may compare the comet
to a globe of iron heated by a forge fire for 13320 hours, to heat it
to a whiteness.
Now we find by calculation from my experiments, that with a forge fire,
we can heat to a whiteness a globe whose diameter is 228342-1/2 inches
in 799200 minutes, and, consequently, the whole mass of the comet to be
heated to the point of iron to a whiteness, during the short time it
was exposed to the heat of the sun, could only be 223342-1/2 inches in
diameter; and even then it must have been struck on all sides, and at
the same time, by the light of the sun. Thus comets, when they approach
the sun, do not receive an immense nor a very durable heat, as Newton
says, and as we at the first view might be inclined to believe. Their
stay is so short in the vicinity of the sun, that their masses have not
time to be heated, and besides only part of their surface is exposed
to it; this part is burnt by the extreme heat, which by calcining and
volatilizing the matter of this surface, drives it outwardly in vapours
and dust from the opposite side to the sun; and what is called the
tail of the comet, is nothing else than the light of the sun rendered
visible, as in a dark room, by those atoms which the heat lengthens as
it is more violent.
But another consideration very different and infinitely more important,
is, that to apply the result of our experiments and calculation to the
comet and earth, we must suppose them composed of matters which would
demand as much time as iron to cool: whereas, in reality, the principal
matters of which the terrestrial globe is composed, such as clay,
stones, &c. cannot possibly take so long.
To satisfy myself on this point, I caused globes of clay and marl to
be made, and having heated them at the same forge until white, I found
that the clay balls of two inches, cooled in 38 minutes so as to be
held in the hand; those of two inches and an half, in 48 minutes; and
those of three inches, in 60 minutes; which being compared with the
time of the refrigeration of iron bullets of the same diameters, give
38 to 80 for two inches, 48 to 102 for two inches and a half, and 60 to
127 for three inches; so that only half the time is required for the
refrigeration of clay, to what is necessary for iron.
I found also, that lumps of clay, or marl, of two inches, refrigerated
so as to be held in the hand in 45 minutes; those of two inches and a
half in 58; and those of three inches in 75, which being compared with
the time of refrigeration of iron bullets of the same diameters, gives
46 to 80 for two inches, 58 to 102 for two inches and a half, and 75 to
127 for three inches, which nearly form the ratio of 9 to 5; so that
for the refrigeration of clay, more than half the time is required than
for iron.
It is necessary to observe, that globes of clay heated white, lost
more of their weight than iron bullets, even to the ninth or tenth
part of their weight: whereas marl heated in the same fire, lost
scarcely any thing, although the whole surface was covered over with
scales, and reduced into glass. As this appeared singular, I repeated
the experiment several times, increasing the fire, and continuing it
longer than for iron; and although it scarcely required a third of the
time to redden marl, to what it did to redden iron, I kept them in the
fire thrice as long as was requisite, to see if they would lose more,
but I found very trifling diminutions; for the globe of two inches
heated for eight minutes, which weighed seven ounces, two drachms,
and thirty grains, before it was put in the fire, lost only forty-one
grains, which does not make a hundredth part of its weight; and that
of three inches, which weighed twenty-four ounces, five drachms, and
thirteen grains, having been heated by the fire for eighteen minutes,
that is nearly as much as iron, lost only seventy-eight grains, which
does not make the hundredth and eighty-first part of its weight. These
losses are so trifling, that it may be looked upon, in general, as
certain that pure clay loses nothing of its weight in the fire; for
those trifling diminutions were certainly occasioned by the ferruginous
parts which were found in the clay, and which were in part destroyed by
the fire. It is also worthy of observation, that the duration of heat
in different matters exposed to the same fire for an equal time, is
always in the same proportion, whether the degree of heat be greater or
smaller.
I have made similar experiments on globes of marble, stone, lead, and
tin, by a heat only strong enough to melt tin, and I found, that iron
refrigerated in eighteen minutes, so as to be able to hold it in the
hand, marble refrigerated to the same degree in twelve minutes, stone
in eleven, lead in nine, and tin in eight. It is not, therefore, in
proportion to their density, as is commonly supposed, that bodies
receive and lose more or less heat, but in an inverse ratio of their
solidity; that is, of their greater or lesser _non fluidity_; so that,
by the same heat, less time is requisite to heat or cool the most dense
fluid.
To prevent the suspicion of vainly dwelling upon assertion, I think it
necessary to remark upon what foundation I build this theory; I have
found that bodies which should heat in ratio of their diameters, could
be only those which were perfectly permeable to heat, and would heat
or cool in the same time; hence, I concluded that fluids, whose parts
are only held together by a slight connection, might approach nearer to
this perfect permeability than solids, whose parts have more cohesion.
In consequence of this, I made experiments, by which I found, that
with the same heat all fluids, however dense they might be, heat and
cool more readily than any solids, however light, so that mercury, for
example, heats much more readily than wood, although it be fifteen or
sixteen times more dense.
This made me perceive that the progress of heat in bodies cannot, in
any case, be made relatively to their density; and I have found by
experience, that this progress, as well in solids as fluids, is made
rather by reason of their fluidity, or in an inverse ratio of their
solidity. I mean by _solidity_ the quality opposite to fluidity; and I
say, that it is in an inverse ratio of this quality that the progress
of heat is made in both bodies; and that they heat or cool so much the
faster as they are the more fluid, and so much the slower as they are
more solid, every other circumstance being equal.
To prove that solidity, taken in this sense, is perfectly independent
of density, I have found, by experience, that the most or least dense
matters, heat or cool more readily than other more or less dense
matters, for example, gold or lead, which are much more dense than iron
and copper, heat and cool much quicker; while tin and marble, which are
not so dense, heat and cool much faster than iron and copper; and there
are likewise many other matters which come under the same description;
so that density is in no manner relative to the scale of the progress
of heat in solid bodies.
It is likewise the same in fluids, for I have observed, that
quicksilver, which is thirteen or fourteen times more dense than water,
nevertheless heats and cools in less time than water; and spirit of
wine, which is less dense than water, heats and cools much quicker;
so that generally the progress of heat in bodies, as well with regard
to the ingress as egress, has no affinity with their density, and is
principally made in the ratio of their fluidity, by extending the
fluidity to a solid; from hence I concluded, that we should know the
real degree of fluidity in bodies, by heating them to the same heat;
for their fluidity would be in a like ratio as that of the time during
which they would receive and lose this heat; and that it would be the
same with solid bodies. They will be so much the more solid, that
is to say, so much the more _non fluids_, as they require more time
to receive and lose this heat, and that almost generally to what I
presume; for I have already tried these experiments on a great number
of different matters, and from them I have made a table, which I have
endeavoured to render as complete and exact as possible.
I caused several globes to be made of an inch diameter with the
greatest possible precision, from the following matters, which nearly
represent the Mineral kingdom.
M. Tillet, of the Academy of Sciences, made the globe of refined gold
at my particular request, and the whole of them weighed as follows:
oz. d. gr.
Gold 6 2 17
Lead 3 6 28
Pure silver 3 3 22
Bismuth 3 0 3
Copper-red 2 7 56
Iron 2 5 10
Tin 2 3 48
Antimony melted, and which had
small cavities on its surface 2 1 34
Fine 2 1 2
Em 1 2 24-1/2
White marble 1 0 25
Pure clay 0 7 24
Marble common of Montbard 0 7 20
White gypsum, improperly called
Alabaster 0 6 36
Calcareous white stone of the quarry
of Anieres, near Dijon 6 6 6
Rock chrystal: it was a little too
small, and had many defects. I
presume that without them it
would have weighed 0 6 22
Common glass 0 6 21
Pure earth, very dry 0 6 16
Oker 0 5 9
Porcelain of the Court de Lauraguais 0 5 2-1/2
White chalk 0 4 49
Cherrywood, which although lighter
than most other woods, is that
which takes in the least fire 0 1 59
I must here observe, that a positive conclusion must not be made of
the exact specific weight of each matter from the preceding table,
for notwithstanding the precaution that was taken to render the
globes equal, yet, as I was obliged to employ different workmen, some
were too large, and others too small. Those which were more than an
inch diameter were diminished, but those of rock chrystal, glass and
porcelain, which were rather too small, we suffered to remain, and only
rejected those of agate, jasper, and porphyry, which were sensibly so.
This precision in size was however not absolutely necessary, for it
could very little alter the result of my experiments.
Previously to ordering these globes, I exposed to a like degree
of fire, a square mass of iron, and another of lead of two inches
diameter, and found, by reiterated essays, that lead heated and
cooled in much less time than iron. I made the same experiment on red
copper, and that required more time to heat and cool than lead, and
less than iron. So that of these three matters, iron appeared the least
accessible to heat, and, at the same time, that which retained it the
longest. From which I learn that the law of the progress of heat in
bodies was not proportionable to their density, since lead, which is
more dense than iron or copper, nevertheless heats and cools in less
time than either. As this object appeared important, I was induced
to have these globes made, and to be more perfectly satisfied of the
progress of heat in a great number of different matters, I always
placed the globes at an inch distance from each other, before the same
fire, or in the same oven, 2, 3, 4, or 5, together with a globe of
tin in the midst of them. In most of my experiments I suffered them
to be exposed to the same active fire till the globe of tin began to
melt, and at that instant they were all removed, and placed on a table
in small cases. I suffered them to cool without moving, often trying
whether I could touch them, and the moment they left off burning, and
I could hold them in my hands half a second, I marked the time which
had passed since I drew them from the fire. I afterwards suffered them
to cool to the actual temperature, of which I endeavoured to judge
by means of touching other small globes of the same matters that had
not been heated. Of all the matters which I put to the trial, there
was only sulphur which melted in a less degree of heat than tin, and
notwithstanding its disagreeable smell I should have taken it for a
term of comparison, but being a brittle matter which diminishes by
friction, I preferred tin, although it required nearly double the heat
to melt.
Having heated together bullets of iron, copper, lead, tin, gres, and
Montbard marble, they cooled in the following order:
_So as to be held in the hand _To actual temperature._
for half a second._
Min. Min.
Tin in 6-1/2 In 16
Lead in 8 In 17
Gres in 9 In 19
Common marble in 10 In 21
Copper in 11-1/2 In 30
Iron in 13 In 38
By a second experiment with a fiercer fire, sufficient to melt the tin
bullet, the five others cooled.
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Lead in 10-1/2 In 42
Gres in 12-1/2 In 46
Common marble 13-1/2 In 50
Copper 19-1/2 In 51
Iron 23-1/2 In 54
By a third experiment, with a less degree of fire than the preceding,
the same bullets with a fresh tin bullet, cooled in the following
manner.
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Tin in 7-1/2 In 25
Lead in 9-1/2 In 25
Gres in 10-1/2 In 37
Common marble 12 In 39
Copper 14 In 44
Iron 17 In 50
From these experiments, which I made with as much precision as
possible, we may conclude, first, that the time of refrigeration of
iron, so as to be held in the hand, is to that of copper : : 53-1/2 :
45, and so to the point of temperature : : 142 : 125.
2dly, That the time of refrigeration of iron, so as to be held in the
hand, is to that of the first refrigeration of common marble : : 53-1/2
: 35-1/2 and their entire refrigeration : : 142 : 110.
3dly, that the time of refrigeration of iron, to that of gres, so as
to be held in the hand, is : : 53-1/2 : 32 and : : 142 : 102-1/2, for
their entire refrigeration.
4thly, That the time of refrigeration of iron to that of lead, so as
to be held in the hand, is : : 53-1/2 : 27 and 142 : 94-1/2 for their
entire refrigeration.
In an oven hot enough to melt tin, although all the coals and cinders
were drawn out, I placed, on a piece of iron wire, five bullets,
distant from one another about nine lines, after which the oven was
shut, and having drawn them out, in about 18 minutes they cooled,
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Melted tin in 8 In 24
Silver in 14 In 40
Gold in 15 In 46
Copper in 16-1/2 In 50
Iron in 18 In 56
In the same oven, but with a slower heat, the same bullets with an
other bullet of tin, cooled,
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Tin in 7 In 20
Silver in 11 In 56
Gold in 12-1/2 In 40
Copper in 14 In 43
Iron in 16-1/2 In 47
In the same oven, but with a still less degree of heat, the same
bullets cooled,
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Tin in 6 In 17
Silver in 9 In 26
Gold in 9-1/2 In 28
Copper in 10 In 31
Iron in 11 In 35
Having placed in the same oven five other bullets, placed the same and
separated from each other, their refrigeration was in the following
proportions.
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Antimony in 6-1/2 In 25
Bismuth in 7 In 26
Lead in 8 In 27
Zinc in 10-1/2 In 30
Emery in 11-1/2 In 38
In the same oven, and in the same manner, another bullet of Bismuth was
placed, with six other bullets, which cooled,
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Antimony in 6 In 23
Bismuth in 6 In 25
Bismuth in 6 In 25
Lead in 7-1/2 In 28
Silver in 9-1/2 In 30
Zinc in 10-1/2 In 32
Gold in 11-1/2 In 34
Emery in 13-1/2 In 39
There was put in the same oven a bullet of glass, another of tin, one
of copper, and one of iron, and they cooled,
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Tin in 8 In 27
Glass in 8-1/2 In 22
Copper in 14 In 42
Iron in 16 In 50
Bullets of gold, glass, porcelain, gypsum, and gres, were heated
together, and cooled,
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Gypsum in 8 In 24
Porcelain in 8-1/2 In 25
Glass in 2 In 26
Gres in 10 In 32
Gold in 14-1/2 In 45
Bullets of silver, common marble, hard stone, white marble, and soft
calcareous stone of Anieres, near Dijon, were heated like the former,
and cooled,
_So as to be held in the hand._ _To actual temperature._
Min. Min.
Soft calcareous
stone in 8 In 25
Hard stone in 10 In 34
Common marble in 11 In 35
White marble in 12 In 36
Silver in 13-1/2 In 40
The whole of these experiments were made with the utmost care and
attention, not only by myself but in the presence of several persons,
who also endeavoured to judge of the first degree of temperature by
holding the bullets for half a second in their hands, and the relations
of which are more exact than those of the actual temperature, because
that being variable the result must sometimes vary also.
With a view to avoid that prolixity which would necessarily attend the
continual repetition in a comparative statement of the refrigeration of
these different bodies, we have connected them in a general table, and
taking 10,000 for the standard of comparison, their differences may be
seen at one view.
A TABLE
OF THE
_Relations of different Mineral Substances._
IRON, with
First Entire
Refrig. Refrig.
Emery 10000 to 9117 -- 9020
Copper ---- to 8512 -- 8702
Gold ---- to 8160 -- 8148
Zinc ---- to 7653 -- 6020
6804
Silver ---- to 7619 -- 7423
Marble White ---- to 6774 -- 6704
Marble common ---- to 6636 -- 6746
Stone calcareous hard ---- to 6617 -- 6274
Gres ---- to 5596 -- 6926
Glass ---- to 5576 -- 5805
Lead ---- to 5143 -- 6482
Tin ---- to 4898 -- 4921
Stone calcareous soft ---- to 4194 -- 4659
Clay ---- to 4198 -- 4490
Bismuth ---- to 3580 -- 4081
Chalk ---- to 3086 -- 3878
Gum ---- to 2325 -- 2817
Wood ---- to 1890 -- 1594
Pumice-stone ---- to 1627 -- 1268
EMERY, with
Copper 10000 to 8519 -- 8148
Gold ---- to 8513 -- 8560
Zinc ---- to 8390 -- 7693
7458
Silver ---- to 7778 -- 7895
Stone calcareous hard ---- to 7304 -- 6963
Gres ---- to 6552 -- 6517
Glass ---- to 5862 -- 5506
Lead ---- to 5718 -- 6643
Zinc ---- to 5658 -- 6000
Clay ---- to 5185 -- 5185
Bismuth ---- to 4949 -- 6060
Antimony ---- to 4540 -- 5827
Oker ---- to 4259 -- 3827
Chalk ---- to 3684 -- 4105
Gypsum ---- to 2368 -- 2947
Wood ---- to 1552 -- 3146
COPPER, with
Gold 10000 to 9136 -- 9194
Zinc ---- to 8571 -- 9250
7619
Silver ---- to 8395 -- 7823
Marble common ---- to 7639 -- 8019
Gres ---- to 7333 -- 8160
Glass ---- to 6667 -- 6567
Lead ---- to 6179 -- 7367
Lead ---- to 6179 -- 7367
Tin 10000 to 5746 -- 6916
Stone calcareous tender ---- to 5168 -- 5633
Clay ---- to 5652 -- 6363
Bismuth ---- to 5686 -- 5959
Antimony ---- to 5130 -- 5808
Oker ---- to 5003 -- 4697
Chalk ---- to 4068 -- 4368
GOLD, with
Zinc 10000 to 2474 -- 9304
8422
Silver ---- to 8936 -- 8686
Marble white ---- to 8101 -- 7863
Marble common ---- to 7342 -- 7434
Stone calcareous hard ---- to 7383 -- 7516
Gres ---- to 7368 -- 7627
Glass ---- to 7103 -- 5232
Lead ---- to 6526 -- 7500
Tin ---- to 6324 -- 6051
Stone calcareous soft ---- to 6087 -- 5811
Clay ---- to 5811 -- 5077
Bismuth ---- to 5658 -- 7043
Porcelain ---- to 5526 -- 5593
Antimony ---- to 5395 -- 6348
Oker ---- to 5349 -- 4462
Chalk ---- to 4571 -- 4452
Gypsum ---- to 2989 -- 3293
ZINC, with
Silver 10000 to 8904 -- 8990
10015
Marble white ---- to 8305 -- 8424
7194
Gres ---- to 6242 -- 7333
5838
Lead ---- to 6051 -- 7947
4940
Tin ---- to 6777 -- 6240
5666
Stone calcareous soft ---- to 5536 -- 7719
4425
Clay ---- to 5484 -- 7458
4373
Bismuth ---- to 5343 -- 7547
4232
Antimony ---- to 5246 -- 6608
4135
Chalk ---- to 3729 -- 5862
2618
Gypsum ---- to 3409 -- 4261
2298
SILVER, with
Marble white 10000 to 8681 -- 9200
Marble common ---- to 7912 -- 9040
Stone calcareous hard ---- to 7436 -- 8580
Gres ---- to 7361 -- 7767
Glass ---- to 7230 -- 7212
Lead ---- to 7154 -- 9184
Tin ---- to 6176 -- 6289
Stone calcareous soft ---- to 6178 -- 6289
Clay ---- to 6034 -- 6710
Bismuth ---- to 6308 -- 8877
Porcelain ---- to 5556 -- 5242
Antimony ---- to 5692 -- 7653
Oker ---- to 5000 -- 5668
Chalk ---- to 4310 -- 5000
Gypsum ---- to 2879 -- 3366
Wood ---- to 2253 -- 1864
Pumice-stone ---- to 2059 -- 1525
WHITE MARBLE, with
Marble common 10000 to 8992 -- 9405
Stone hard ---- to 8594 -- 9130
Gres ---- to 8286 -- 8990
Lead ---- to 7604 -- 5555
Tin ---- to 7143 -- 6792
Stone calcareous soft ---- to 6792 -- 7281
Clay ---- to 6400 -- 6286
Antimony ---- to 6286 -- 6792
Oker ---- to 5400 -- 5571
Gypsum ---- to 4920 -- 5116
Wood ---- to 2200 -- 2857
COMMON MARBLE, with
Stone hard 10000 to 9483 -- 9665
Gres ---- to 8767 -- 9273
Lead ---- to 7671 -- 8590
Tin ---- to 7424 -- 6666
Stone soft ---- to 7327 -- 7959
Clay ---- to 7272 -- 7213
Antimony ---- to 6279 -- 8333
Oker ---- to 6136 -- 6393
Chalk ---- to 5581 -- 6333
Wood ---- to 2500 -- 3279
HARD CALCAREOUS STONE, with
Gres 10000 to 9268 -- 9355
Glass ---- to 8710 -- 8352
Lead ---- to 8571 -- 7931
Tin ---- to 1095 -- 7931
Stone soft ---- to 8000 -- 8095
Clay ---- to 6190 -- 6897
Oker ---- to 4762 -- 5517
Wood ---- to 2195 -- 4516
GRES, with
Glass 10000 to 9324 -- 7939
Lead ---- to 8561 -- 8950
Tin ---- to 7667 -- 7633
Stone soft ---- to 7644 -- 7193
Porcelain ---- to 7364 -- 7059
Antimony ---- to 7333 -- 6170
Gypsum ---- to 4568 -- 5000
Wood ---- to 2368 -- 4828
GLASS, with
Lead 10000 to 9318 -- 8548
Tin ---- to 9107 -- 8679
Clay ---- to 7938 -- 7643
Porcelain ---- to 7692 -- 8863
Oker ---- to 6289 -- 6500
Chalk ---- to 6104 -- 6195
Gypsum ---- to 4160 -- 6011
Wood ---- to 2647 -- 5514
LEAD, with
Tin 10000 to 8695 -- 8333
Stone soft ---- to 8437 -- 7192
Clay ---- to 7878 -- 8536
Bismuth ---- to 8698 -- 8750
Antimony ---- to 8241 -- 8201
Oker ---- to 6060 -- 7073
Chalk ---- to 5714 -- 6111
Gypsum ---- to 4736 -- 5714
TIN, with
Clay 10000 to 8823 -- 9524
Bismuth ---- to 8889 -- 9400
Antimony ---- to 8710 -- 9156
Oker ---- to 5882 -- 7619
Chalk ---- to 6394 -- 6842
Gypsum ---- to 4090 -- 4912
STONE CALCAREOUS SOFT, with
Antimony 10000 to 7742 -- 9542
Chalk ---- to 7288 -- 7312
Gypsum ---- to 4182 -- 5211
CLAY, with
Bismuth 10000 to 8870 -- 9416
Oker ---- to 8400 -- 8571
Chalk ---- to 7701 -- 8000
Gypsum ---- to 5185 -- 8055
Wood ---- to 3437 -- 4545
BISMUTH, with
Antimony 10000 to 9349 -- 9572
Oker ---- to 8846 -- 7380
Chalk ---- to 8020 -- 9500
PORCELAIN, with
Gypsum 10000 to 5301 -- 6500
ANTIMONY, with
Chalk 10000 to 8431 -- 7391
Gypsum ---- to 3833 -- 5476
OKER, with
Chalk 10000 to 8954 -- 8889
Gypsum ---- to 6364 -- 9062
Wood ---- to 4074 -- 5128
CHALK, with
Gypsum 10000 to 6667 -- 7920
GYPSUM, with
Wood 10000 to 8000 -- 5260
Pumice-stone ---- to 7099 -- 4560
WOOD, with
Pumice-stone 10000 to 8750 -- 8182
Notwithstanding the assiduity I used in my experiments, and the care
I took to render the relations exact, I own there are still some
imperfections in the foregoing table; but the defects are trivial,
and do not much influence the general results; for example, it will
easily be perceived, that the relation of zinc to lead being 10,000
to 6,051, that of zinc to tin should be less than 6,000, whereas it
is found 6,777 in the table. It is the same with respect of silver
to bismuth, which ought to be less than 6,308, and also with regard
of lead to clay, which ought to be more than 8,000, but in the table
is only 7,878. This difference proceeded from the leaden and bismuth
bullets not being always the same; they melted, as well as those of tin
and antimony, and, therefore, could not fail to produce variations,
the greatest of which are the three I have just remarked. It was not
possible for me to do better; the different bullets of lead, tin,
bismuth, and antimony, which I successively made use of, were made in
the same manner, but the matter of each might be somewhat different,
according to the quantity of the alloy in the lead and tin, for I had
pure tin only for the two first bullets; besides, there remains very
often a small cavity in the melted bullet, and these little causes are
sufficient to produce the little differences which may be remarked in
the table.
On the whole, to draw from these experiments all the profit that can be
expected, the matters which compose their object must be divided into
four classes, viz. 1. Metals. 2. Semi-metals and Metallic Minerals. 3.
Vitreous and Vitrescible Substances. And 4. Calcareous and Calcinable
substances. Afterwards the matters of each class must be compared
between themselves to discover the cause, or causes, or the order which
follows the progress of heat in each, and then with each other, in
order to deduce some general results.
First. The order of the six metals, according to their _density_, is
tin, iron, copper, silver, lead, and gold; whereas the order in which
they receive and lose their heat is tin, lead, silver, gold, copper,
and iron; so that in tin alone it retains its place.
The progress and duration of heat in metals does not then follow the
order of their density, except in tin, which being the least dense,
is also that which soonest loses its heat; but the order of the five
other metals demonstrates that it is in relation to their fusibility
that they all receive and loose heat; for iron is more difficult to
melt than copper, copper more than gold, gold more than silver, silver
more than lead, lead more than tin; and therefore we may conclude that
it is only by chance if the density and fusibility of tin be found
so united as to place it in the last rank. Nevertheless, it would be
advancing too much to pretend that we must attribute all to fusibility,
and nothing to density. Nature never deprives herself of one of her
properties in favour of another in an absolute manner; that is to say,
in a mode that the first has not any influence on the second. Thus,
density may be of some weight in the progress of heat; but we may
safely affirm, that in the six metals it has very little comparatively
with fusibility.
This fact was neither known to chemists nor naturalists; they did not
even imagine that gold which is more than twice as dense as iron,
nevertheless loses its heat near a third sooner. It is the same with
lead, silver, and copper, which are all more dense than iron, and
which, like gold, heat and cool more readily; for though the object of
this, second memoir was only refrigeration, yet the experiments of the
one that preceded it demonstrate, that there is ingress and egress of
heat in bodies, and that those which receive it most quickly also lose
it the soonest.
If we reflect on the real principles of density, and the cause of
fusibility, we shall perceive, that density depends absolutely on the
quantity of matter which Nature places in a given space; that the more
she can make it enter therein, the more density there will be, and
that gold, in this respect, is of all substances, that which contains
the most matter relatively to its volume. It is for this reason that
it has been hitherto thought, that more time is required to heat or
cool gold than other metals; and it is natural enough to suppose, that
containing double or treble the matter in the same volume, double or
treble time would be required to penetrate it with heat; nay this would
be true, if in every substance the constituent parts were of the same
figure and ranged the same. But in the most dense the molecules of
matter are, probably, of a figure sufficiently regular not to leave
very void places between them; in others which are not so dense, and
their figures more irregular, more vacuities are left, and in the
lightest, the molecules being few, and most likely of a very irregular
figure, a thousand times more void is found than plenitude; for it may
be demonstrated by other experiments, that the volume of even the most
dense substance contains more void space than full matter.
Now, the principal cause of fusibility is the facility which the
particles of heat find in separating these molecules of full matter
from each other; let the sum of the vacuities be greater or less, which
causes density or lightness, it is indifferent to the separation of
the molecules which constitute the plenitude; and the greater or less
fusibility depends entirely on the power of coherence which retains
the massive parts united, and opposes itself more or less to their
separation. The dilatation of the total volume is the first degree of
the action of heat; and in different metals it is made in the same
order as the fusion of the mass, which is performed by a greater degree
of heat or fire. Tin, which melts the most readily, is also that which
dilates the quickest; and iron, which is the most difficult of all to
melt, is likewise that whose dilatation is the slowest.
After these general positions, which appear clear, precise, and founded
on experiments that nothing can contradict, it might be imagined that
ductility would follow the order of fusibility, because the greater
or less ductility seems to depend on the greater or less adhesion of
the parts in each metal; nevertheless, ductility seems to have as much
connection with the order of density, as with that of their fusibility.
I would even affirm that it is in a ratio composed of the two others,
but that would be only by estimation, and a presumption which is,
perhaps not founded; for it is not so easy to exactly determine the
different degrees of fusibility, as those of density; and as ductility
participates of both, and varies according to circumstances, we have
not as yet acquired the necessary knowledge to pronounce affirmatively
on this subject, though it is most certainly of sufficient importance
to merit particular researches. The same metal when cold gives very
different results to what it does when hot, although treated in
the same manner. Malleability is the first mark of ductility; but
that gives only an imperfect idea of the point to which ductility
may extend; nor can simple lead, the most malleable metal, be drawn
into such fine threads as gold, or even as iron, which is the least
malleable. Besides we must assist the ductility of metals with the
addition of fire, without which they become brittle: even iron,
although the most robust, is brittle like the rest. Thus the ductility
of one metal, and the extent of continuity which it can support, depend
not only on its density and fusibility, but also on the manner and
space in which it is treated, and of the addition of heat or fire which
is properly given to it.
II. By comparing those substances which we term _semi-metals_ and
_metallic minerals_, which want ductility, we shall perceive, that
the order of their density is emery, zinc, antimony and bismuth, and
that in which they receive and lose heat, is antimony, bismuth, zinc,
and emery; and which does not in any measure follow the order of
their density, but rather that of their fusibility. Emery, which is a
ferruginous mineral, although as dense again as bismuth, retains heat
longer. Zinc, which is lighter than antimony or bismuth, retains heat
longer than either. Antimony and bismuth, receive and keep it nearly
alike. There are, therefore, semi-metals, and metallic minerals, which,
like metals, receive and lose heat nearly in the same relation as their
fusibility, and partake very little of their density.
But by joining the six metals, and the four semi-metals, or metallic
minerals, which I have tried, we shall find the order of the densities
of these ten mineral substances to be emery, zinc, antimony, tin,
iron, copper, bismuth, silver, lead and gold. And that the order in
which these substances heat and cool, is antimony, bismuth, tin,
lead, silver, zinc, gold, copper, emery and iron, in which there are
two things that do not appear to perfectly agree with the order of
fusibility.
First, Antimony, which, according to Newton, should heat and cool
slower than lead, since by his experiments it requires ten degrees of
the same heat to fuse, of which eight are sufficient for lead; whereas
by my experiments antimony is found to heat and cool quicker than
lead. But it should be observed that Newton made use of the regulus of
antimony, and that I employed only melted antimony in experiments. Now
this regulus of antimony, or native antimony, is much more difficult
to fuse than antimony which has already undergone a first fusion,
therefore that does not make an exception to the rule. On the whole, I
do not know what relation native antimony, or regulus of antimony, may
have with the other matters I have heated and cooled; but I presume,
from the experiments of Newton, that it heats and cools slower than
lead.
Secondly, it is pretended, that zinc fuses more easily than silver,
consequently it should be found before silver in the order indicated
by experiments, if this order were in all cases relative to that of
fusibility; and I own that this semi-metal seems, at the first glance,
to make an exception to the law which is followed by all the others;
but it must be observed, that the difference given by my experiments
between zinc and silver is very trifling. The small globe of silver
which I made use of was of the purest silver, without the least mixture
of copper; but I had my doubts whether that of zinc were entirely
free from copper, or some other metal less fusible; and therefore,
after all my experiments, I returned the globe of zinc to M. Rouelle,
a celebrated professor of chemistry, requesting him carefully to
examine it, which having done, after several trials, he found a pretty
considerable quantity of iron, or saffron of steel in it.
I have, therefore, had the satisfaction of seeing that not only my own
supposition was well founded, but also that my experiments have been
made with sufficient precision to evince a mixture. Thus zinc exactly
follows the order of fusibility, like the other metals and semi-metals,
in the progress of heat, and does not make any exception to the rule.
It cannot therefore, in general, be said that the progress of heat in
metals, semi-metals, and metallic minerals, is in the same ratio, or
even nearly to that of their fusibility.
III. The Vitrescible and Vitreous Matters, which I tried, being ranged
according to their density, are, pumice-stone, porcelain, oker, clay,
glass, rock-chrystal, and gres, for I must observe, that although
chrystal is not set down in the table of the weight of each matter but
for six drachms 22 grains, it must be supposed one drachm heavier,
because it was sensibly too small; and it was for this reason that I
excluded it from the general table of relations; nevertheless, as the
general result agrees with the rest, I can present the following as the
order in which these different substances are cooled:
Pumice-stone, oker, porcelain, clay, glass, crystal and gres, is
according to that of their density, for the oker is here before the
porcelain only because, being a fusible matter, it diminished by the
friction it underwent in the experiments, and, besides, their density
differs so little that they may be looked upon as equal.
Thus the law of the progress of heat in vitrescible and vitreous
matters is relative to the order of their density, and has little or no
relation with their fusibility but by the heat required to fuse those
substances being in an almost equal degree, and the particular degree
of their different fusibility being so near each other that an order
of distinct terms cannot be made; thus their almost equal fusibility
making only one term, which is the extreme of this order, we must not
be astonished that the progress of heat here follows the order of
density, and that these different substances, which are all equally
difficult to fuse, heat and cool more or less quick in proportion to
the matter they contain.
It may be objected to me that glass fuses more easily than clay,
porcelain, oker, and pumice-stone, which, nevertheless, heat and cool
in less time than glass; but the objection will fail when we reflect,
that to fuse glass it is requisite to have a very fierce fire, the
heat of which is so remote from the degrees which glass receives in
our experiments on refrigeration, that it cannot have any influence
on them. Besides, by powdering clay, porcelain, and pumice-stone, and
by giving them their analogous fusers, as we give to sand to convert
it into glass, it is more than probable that we should fuse all the
matters in the same degree of fire, and that, consequently we must look
upon it as equal, or almost equal, with their resistance to fusion;
and it is for this reason that the law of the progress of heat in these
matters is found proportionable to the order of their density.
IV. Calcareous matters, ranged according to the order of their density,
are, chalk, soft stone, hard stone, common marble, and white marble,
which is the same as that of their density. The fusibility is not
here of any weight, because it requires at first a very great degree
of fire to calcine them; and although the calcination divides the
parts, we must look upon the effect only as a first degree and not
as a complete fusion. The whole power of the best burning mirrors is
scarcely sufficient to perform it. I have melted and reduced into a
kind of glass some of these calcareous matters; and I am convinced that
these matters may, like all the rest, be reduced ulteriorly into glass,
without employing for this purpose any fusing matter, and only by the
force of a fire superior to that of our furnaces; consequently the
common term of their fusibility is still more remote, and more extreme,
than that of vitreous matters, and it is for this reason that they also
follow more exactly the order of density in the progress of heat.
White gypsum, improperly called alabaster, is a matter which calcines
like all other plasters by a more moderate heat than that which is
necessary for the calcination of calcareous matters, and it follows the
order of density in the progress of heat which it receives or loses,
for although much more dense than chalk, and a little more so than
white calcareous stone, it heats and cools more readily than either of
those matters. This demonstrates that the more or less easy calcination
and fusion produces the same effects relatively to the progress of
heat. Gypsous matters do not require so much fire to calcine as
calcareous, and it is for this reason that, although more dense, they
heat and cool much quicker.
Thus it may be concluded, that, in general, the _progress of heat in
all Mineral Substances is always nearly in a ratio of their greater or
less facility to calcine, or melt_: but that when their calcination, or
their fusion, are _equally difficult_, and _that they require a degree
of extreme heat_, then the _progress of heat is made according to the
order of their density_.
I have deposited in the Royal Cabinet the globes of gold, silver, and
of all the other metallic and mineral substances which served for the
preceding experiments, that if the truth of their results, and the
general consequences which I have deduced, be doubted, there may be an
opportunity of rendering them more authentic.
OBSERVATIONS ON THE NATURE OF PLATINA.
We have already seen, that of all the Mineral substances which I
subjected to trial it was not the most dense, but the least fusible,
which required the longest time to receive and lose heat. Iron and
emery, which are the most difficult matters to fuse, are, at the same
time, those that heat and cool the slowest. There is nothing except
platina that is accessible to heat, which retains it longer than iron.
This mineral, (which has not long been publicly mentioned) appears,
however, to be more difficult to fuse; the fire of the best furnaces
is not
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