Chap. I. On Heat or Caloric
The most probable opinion concerning the nature of caloric, is, that of its being an
elastic fluid of great subtility, the particles of which repel one another, but are
attracted by all other bodies.
When all surrounding bodies are of one temperature, then the heat attached to them is
in a quiescent state; the absolute quantities of heat in any two bodies in this case are
not equal, whether we take the bodies of equal weights or of equal bulks. Each kind of
matter has its peculiar affinity for heat, by which it requires a certain portion of the
fluid, in order to be in equilibrium with other bodies at a certain temperature. Were the whole
quantities of heat in bodies of equal weight or bulk, or even the relative
quantities, accurately ascertained, for any temperature, the numbers expressing those
quantities would constitute a table of specific heats, analogous to a table of specific
gravities, and would be an important acquisition to science. Attempts of this kind
have been made with very considerable success.
Whether the specific heats, could they be thus obtained for one temperature, would
express the relation at every other temperature, whilst the bodies retained their form, is
an enquiry of some moment. From the experiments hitherto made there seems little doubt of
its being nearly so; but it is perhaps more correct to deduce the specific heat of bodies
from equal bulks than from equal weights. It is very certain that the two
methods will not give precisely the same results, because the expansions of different
bodies by equal increments of temperature are not the same. But before this subject can
well be considered, we should first settle what is intended to be meant by the word
Chap. II. On the Constitution of Bodies.
There are three distinctions in the kinds of bodies, or three states, which have more
especially claimed the attention of philosophical chemists; namely, those which are marked
by the terms elastic fluids, liquids, and solids. A very famous instance is
exhibited to us in water, of a body, which, in certain circumstances, is capable of
assuming all the three states. In steam we recognise a perfectly elastic fluid, in water a
perfect liquid, and in ice a complete solid. These observations have tacitly led to the
conclusion which seems universally adopted, that all bodies of sensible magnitude, whether
liquid or solid, are constituted of a vast number of extremely small particles, or atoms
of matter bound together by a force of attraction, which is more or less powerful
according to circumstances, and which as it endeavours to prevent their separation, is
very properly called in that view, attraction of cohesion; but as it collects them
from a dispersed state (as from steam into water) it is called, attraction of
aggregation, or more simply affinity. Whatever names it may go by, they still
signify one and the same power. It is not my design to call in question this conclusion,
which appears completely satisfactory; but to shew that we have hitherto made no use of
it, and that the consequence of the neglect, has been a very obscure view of chemical
agency, which is daily growing more so in proportion to the new lights attempted to be
thrown upon it.
The opinions I more particularly allude to, are those of Berthollet on the Laws of
chemical affinity; such as that chemical affinity is proportional to the mass, and that in
all chemical unions, there exist insensible gradations in the proportions of the
constituent principles. The inconsistence of these opinions, both with reason and
observation, cannot, I think, fail to strike every one who takes a proper view of the
Whether the ultimate particles of a body, such as water, are all alike, that is, of the
same figure, weight, &c. is a question of some importance. From what is known, we have
no reason to apprehend a diversity in the particulars: if it does exist in water, it must
equally exist in the elements constituting water, namely, hydrogen and oxygen. Now it is
scarcely possible to conceive how the aggregates of dissimilar particles should be so
uniformly the same. If some of the particles of water were heavier than others, if a
parcel of the liquid on any occasion were constituted principally of these heavier
particles, it must be supposed to affect the specific gravity of the mass, a circumstance
not known. Similar observations may be made on other substances. Therefore we may conclude
that the ultimate particles of all homogeneous bodies are perfectly alike in weight,
figure, &c. In other words, every particle of water is like every other particle
of water; every particle of hydrogen is like every other particle of hydrogen, &c.
Besides the force of attraction, which, in one character or another, belongs
universally to ponderable bodies, we find another force that is likewise universal, or
acts upon all matter which comes under our cognisance, namely, a force of repulsion. This
is now generally, and I think properly, ascribed to the agency of heat. An atmosphere of
this subtile fluid constantly surrounds the atoms of all bodies, and prevents them from
being drawn into actual contact. This appears to be satisfactorily proved by the
observation, that the bulk of a body may be diminished by abstracting some of its heat:
But from what has been stated in the last section, it should seem that enlargement and
diminution of bulk depend perhaps more on the arrangement, than on the size of the
ultimate particles. Be this as it may, we cannot avoid inferring from the preceding
doctrine on heat, and particularly from the section on the natural zero of temperature,
that solid bodies, such as ice, contain a large portion, perhaps 4/5 of the heat which the
same are found to contain in an elastic state, as steam.
We are now to consider how these two great antagonist powers of attraction and
repulsion are adjusted, so as to allow of the three different states of elastic fluids,
liquids, and solids. We shall divide the subject into four Sections; namely, first, on
the constitution of pure elastic fluids; second, on the constitution of mixed
elastic fluids; third, on the constitution of liquids, and fourth, on the
constitution of solids.
CHAP. III. On Chemical Synthesis.
When any body exists in the elastic state, its ultimate particles are separated from
each other to a much greater distance than in any other state; each particle occupies the
centre of a comparatively large sphere, and supports its dignity by keeping all the rest,
which by their gravity, or otherwise are disposed to encroach up it, at a respectful
distance. When we attempt to conceive the number of particles in an atmosphere, it
is somewhat like attempting to conceive the number of stars in the universe; we are
confounded with the thought. But if we limit the subject, by taking a given volume of any
gas, we seem persuaded that, let the divisions be ever so minute, the number of particles
must be finite; just as in a given space of the universe, the number of stars and planets
cannot be infinite.
Chemical analysis and synthesis go no farther than to the separation of particles one
from another, and to their reunion. No new creation or destruction of matter is within the
reach of chemical agency. We might as well attempt to introduce a new planet into the
solar system, or to annihilate one already in existence, as to create or destroy a
particle of hydrogen. All the changes we can produce, consist in separating particles that
are in a state of cohesion or combination, and joining those that were previously at a
In all chemical investigations, it has justly been considered an important object to
ascertain the relative weights of the simples which constitute a compound. But
unfortunately the enquiry has terminated here; whereas from the relative weights in the
mass, the relative weights of the ultimate particles or atoms of the bodies might have
been inferred, from which their number and weight in various other compounds would appear,
in order to assist and to guide future investigations, and to correct their results. Now
it is one great object of this work, to shew the importance and advantage of ascertaining the
relative weights of the ultimate particles, both of simple and compound bodies, the number
of simple elementary particles which constitute one compound particle, and the number of
less compound particles which enter into the formation of one more compound particle.
If there are two bodies, A and B, which are disposed to combine, the following is the
order in which the combinations may take place, beginning with the most simple: namely,
- 1 atom of A + 1 atom of B = 1 atom of C, binary.
- 1 atom of A + 2 atoms of B = 1 atom of D, ternary.
- 2 atoms of A + 1 atom of B = 1 atom of E, ternary.
- 1 atom of A + 3 atoms of B = 1 atom of F, quarternary.
- 3 atoms of A + 1 atom of B = 1 atom of G, quarternary.
- &c. &c.
The following general rules may be adopted as guides in all our investigations
respecting chemical synthesis.
- 1st. When only one combination of two bodies can be obtained, it must be presumed to be
a binary one, unless some other cause appear to the contrary.
- 2d. When two combinations are observed, they must be presumed to be a binary and
- 3d. When three combinations are observed, they must be presumed to be a binary,
and the other two ternary.
- 4th. When four combinations are observed, we should expect one binary, two ternary,
and one quarternary, &c.
- 5th. A binary compound should always be specifically heavier than the mere
mixture of its two ingredients.
- 6th. A ternary compound should be specifically heavier than the mixture of a
binary and a simple, which would, if combined, constitute it; &c.
- 7th. The above rules and observations equally apply, when two bodies, such as C and D, D
and E, &c. are combined.
application of these rules, to the chemical facts already well ascertained, we deduce the
following conclusions; 1st. That water is a binary compound of hydrogen and oxygen, and
the relative weights of the two elementary atoms are as 1:7, nearly; 2d. That ammonia is a
binary compound of hydrogen and azote, and the relative weights of the two atoms are as
1:5, nearly; 3d. That nitrous gas is a binary compound of azote and oxygen, the atoms of
which weigh 5 and 7 respectively; that nitric acid is a binary or ternary compound
according as it is derived, and consists of one atom of azote and two of oxygen, together
weighing 19; that nitrous oxide is a compound similar to nitric acid, and consists of one
atom of oxygen and two of azote, weighing 17; that nitrous acid is a binary compound of
nitric acid and nitrous gas, weighing 31; that oxynitric acid is a binary compound of
nitric acid with oxygen, weighing 26; 4th. That carbonic oxide is a binary compound,
consisting of one atom of charcoal, and one of oxygen, together weighing nearly 12; that
carbonic acid is a ternary compound, (but sometimes binary) consisting of one atom of
charcoal, and two of oxygen, weighing 19; &c. &c. In all these cases the weights
are expressed in atoms of hydrogen, each of which is denoted by unity.
In the sequel, the facts and experiments from which these conclusions are derived, will
be detailed; as well as a great variety of others from which are inferred the constitution
and weight of the ultimate particles of the principal acids, the alkalis, the earths, the
metals, the metallic oxides and sulphurets, the long train of neutral salts, and in short,
all the chemical compounds which have hitherto obtained a tolerably good analysis. Several
of the conclusions will be supported by original experiments.
From the novelty as well as importance of the ideas suggested in this chapter, it is
deemed expedient to give plates, exhibiting the mode of combination in some of the more
simple cases. A specimen of these accompanies this first part. The elements or atoms of
such bodies as are conceived at present to be simple, are denoted by a small circle, with
some distinctive mark; and the combinations consist in the juxta-position of two or more
of these; when three or more particles of elastic fluids are combined together in one, it
is supposed that the particles of the same kind repel each other, and therefore take their
||Hydrogen, its relative weight
||Carbone or charcoal
|An atom of water or steam, composed of 1 of oxygen and 1 of hydrogen,
retained in physical contact by a strong affinity, and supposed to be surrounded by a
common atmosphere of heat; its relative weight = 8
||An atom of ammonia, composed of 1 of azote and 1 of hydrogen
||An atom of nitrous gas, composed of 1 of azote and 1 of oxygen
||An atom of olefiant gas, composed of 1 of carbone and 1 of hydrogen
||An atom of carbonic oxide composed of 1 of carbone and 1 of oxygen
||An atom of nitrous oxide, 2 azote + 1 oxygen
||An atom of nitric acid, 1 azote + 2 oxygen
||An atom of carbonic acid, 1 carbone + 2 hydrogen
||An atom of carburretted hydrogen, 1 carbone + 2 hydrogen
||An atom of oxynitric acid, 1 azote + 3 oxygen
||An atom of sulphuric acid, 1 sulphur + 3 oxygen
||An atom of sulphuretted hydrogen, 1 sulphur + 3 hydrogen
||An atom of alcohol, 3 carbone, + 1 hydrogen
||An atom of nitrous acid, 1 nitric acid + 1 nitrous gas
||An atom of acetous acid, 2 carbone + 2 water
||An atom of nitrate of ammonia, 1 nitric acid + 1 amonia + 1 water
||An atom of sugar, 1 alcohol + 1 carbonic acid