pheres at 60° F. while the bisulphuretted hydrogen becomes liquid, or semi solid, without any pressure.

By the affinity of ponderable matter for caloric, its atoms are approximated and held together: by its elastic or self-repelling property, it separates them from each other, as in gasefaction, explosion, and all decompositions. The fact that Philosophers have overlooked this affinity by which caloric is concentrated around the particles of liquids and solids, resolves the problem of contradictions by which the theory of caloric has been so long perplexed, and explains why many have doubted its materiality-why the phenomena of combustion, explosion, cohesion, and chemical affinity have not been understood.

I have shown, that caloric is the cause of repulsion in steam and all gases; in vaporization, combustion, and the expansive force of detonating compounds: and that this elastic force is counteracted and diminished, or vanquished by its affinity for gravitating matter.

The ancient philosophers of Greece often referred to an agency, by which they supposed that all nature was perpetually tending to a general dissolution: but being restrained by the overpowering concord of things, (by which they meant attraction,) the result of the conflict was the beautiful order and harmony of the world.

This doctrine throws a clear and full light on

all the powers, motions, combinations and decompositions of the elements by which we are surrounded and sustained; and, when perfectly unfolded in all its relations, will be found to furnish a simple and rational interpretation of the book of nature.

Constitution of Liquids.

It has been shown in the preceding chapter, that there is an intimate relation between the elastic force of gases, and the proportions of igneous æther, which surrounds their atoms that hydrogen contains a larger amount of caloric, in proportion to the quantity of ponderable matter, than any other known body, and possesses a corresponding degree of expansive force: but that when it unites chemically with oxygen, it gives out a large proportion of caloric, by which its volume and elasticity are diminished.

It has also been shown, that other things being equal, the elastic force of other gaseous bodies is in proportion to the amount of igneous matter which is combined with any given quantity of ponderable matter.

I shall now proceed to show, that the lightest and most volatile liquids are composed of elements which contain a large proportion of caloric around their atoms. I am not aware that any one, since the time of Boyle and Newton,

has attempted to explain why liquids differ so greatly in their volatility. Boyle supposed that their tenacity was owing to the grossness of their particles, while Newton referred their volatility to the smallness of their particles. Neither of these hypotheses, which are nearly the same, is in accordance with the present state of science. The proximate atoms of water are less than those of alcohol, æther, and various other liquids that are more elastic and volatile at the same temperatures. The atoms of nitrous and nitric acids, of sulphuretted and phosphuretted hydrogen, of chlorine, hydrochloric acid, and many other gaseous bodies, are larger than those of carbon, sulphur, phosphorus, silicium, calcium, &c. Yet the former are much more volatile and elastic than the latter. The atoms of ætherine, sulphurous acid, muriatic æther, (which is composed of ætherine and hydrochloric acid) protoxide of chlorine, &c. are larger than those of water or hydrocyanic acid, the elasticity of which is much inferior.*

Such facts prove conclusively, that the elastic force of gases and liquids is not determined alone

* Lucretius observes that light passes through scraped horn, which wine and water will not do, because the particles of the latter are too large; but that water and wine percolate strainers more readily than oils, because the latter are composed of larger particles, or of particles that are hooked. (De Natura Rerum, Book II.)

by the size of their proximate atoms, but by their relations to a self-repelling fluid.

There is a class of liquids which are composed chiefly of hydrogen and carbon, that seem to form a connecting link between gases and more fixed bodies. They are generally much lighter than water, and exceedingly volatile. Such are Faraday's ætherine and bicarburet of hydrogen, spirit of gum elastic, paraffine,and naphtha. Æther, alcohol, pyro-acetic spirit, acetic æther, and most of the essential oils, which are composed of carbon and hydrogen, united with small proportions of oxygen, are lighter than water, and some of them highly volatile. There are also a few combinations of hydrogen and carbon with nitrogen, chlorine, and even iodine, that are very volatile, as nitrous æther, hydrocyanic acid, muriatic, and hydriodic æthers. There cannot be a doubt that all such liquids owe their volatility to the same cause which determines the elastic force of gases. Accordingly, we find, that ætherine, the lightest of them all, boils or expands rapidly into the gaseous state, under the pressure of the atmosphere below 32°. Common æther boils at 96°, muriatic æther at 60°, nitrous æther at 60°, and acetic æther at 105°, while alcohol boils at 173°.* But when the pressure of the atmosphere is removed, as under an ex

* With a view of ascertaining how far the rationale of such phenomena had occupied the attention of philosophers, I took an opportunity of asking a distinguished professor and author in

hausted receiver, the elastic force of the caloric which surrounds their particles, expands them rapidly into vapour at 145° below their boiling points under the pressure of the atmosphere. In all such cases, liquids are expanded into the gaseous state by the elastic force of their latent constituent caloric, which is thus diffused and carried off, by which intense cold is produced. In vacuo, pure æther is rapidly expanded into vapour at 46°, alcohol at 28°, and water at 67°— from which it follows, that they are all elastic fluids like gases, but in a less degree; and that if their elasticity were not restrained by the pressure of the atmosphere, they would boil at ordinary temperatures, until the process were checked by the pressure of their own atmospheres.

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By reference to a subsequent Table, it will be seen that æther is composed of 5 atoms of hydrogen, 4 of carbon, and 1 of oxygen; or 2 atoms of olefiant gas to one of water; and that

London, why æther, alcohol, &c. were more volatile than water, and the latter than sulphuric acid : after pausing a few moments, he replied, that "he supposed it was owing to the smallness of their cohesion," the reason of which remained in statu quo.

I have thought proper to relate this circumstance, because the present systems of chemistry and physics are full of such definitions and explanations, the fundamental reason of things being overlooked. When a teacher is asked by his pupil why men can see through water, glass, and many other hard dense bodies, he answers with the utmost self-complacency, because they are transparent, and there is an end of the matter.