: Elements of Chemistry In a New Systematic Order Containing all the Modern Discoveries by Lavoisier Antoine Laurent Kerr Robert Translator - Chemistry Early works to 1800 Chemistry

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f the French Academy of Sciences for that year, p. 420.

Chemical Nomenclature.

It would have been more satisfactory if the Author had specified the degrees of the thermometer at which these heights of the mercury in the barometer are produced.

Vide Memoirs of the French Academy, anno 1780, p. 335.--A.

The better to determine our ideas relating to this subject, which has not hitherto been sufficiently considered, let us, for a moment, conceive what change would take place in the various substances which compose our earth, if its temperature were suddenly altered. If, for instance, we were suddenly transported into the region of the planet Mercury, where probably the common temperature is much superior to that of boiling water, the water of the earth, and all the other fluids which are susceptible of the gasseous state, at a temperature near to that of boiling water, even quicksilver itself, would become rarified; and all these substances would be changed into permanent a?riform fluids or gasses, which would become part of the new atmosphere. These new species of airs or gasses would mix with those already existing, and certain reciprocal decompositions and new combinations would take place, until such time as all the elective attractions or affinities subsisting amongst all these new and old gasseous substances had operated fully; after which, the elementary principles composing these gasses, being saturated, would remain at rest. We must attend to this, however, that, even in the above hypothetical situation, certain bounds would occur to the evaporation of these substances, produced by that very evaporation itself; for as, in proportion to the increase of elastic fluids, the pressure of the atmosphere would be augmented, as every degree of pressure tends, in some measure, to prevent evaporation, and as even the most evaporable fluids can resist the operation of a very high temperature without evaporating, if prevented by a proportionally stronger compression, water and all other liquids being able to sustain a red heat in Papin's digester; we must admit, that the new atmosphere would at last arrive at such a degree of weight, that the water which had not hitherto evaporated would cease to boil, and, of consequence, would remain liquid; so that, even upon this supposition, as in all others of the same nature, the increasing gravity of the atmosphere would find certain limits which it could not exceed. We might even extend these reflections greatly farther, and examine what change might be produced in such situations upon stones, salts, and the greater part of the fusible substances which compose the mass of our earth. These would be softened, fused, and changed into fluids, &c.: But these speculations carry me from my object, to which I hasten to return.

Amongst the fluids with which we are acquainted, some, as water and alkohol, are susceptible of mixing with each other in all proportions; whereas others, on the contrary, as quicksilver, water, and oil, can only form a momentary union; and, after being mixed together, separate and arrange themselves according to their specific gravities. The same thing ought to, or at least may, take place in the atmosphere. It is possible, and even extremely probable, that, both at the first creation, and every day, gasses are formed, which are difficultly miscible with atmospheric air, and are continually separating from it. If these gasses be specifically lighter than the general atmospheric mass, they must, of course, gather in the higher regions, and form strata that float upon the common air. The phenomena which accompany igneous meteors induce me to believe, that there exists in the upper parts of our atmosphere a stratum of inflammable fluid in contact with those strata of air which produce the phenomena of the aurora borealis and other fiery meteors.--I mean hereafter to pursue this subject in a separate treatise.

FOOTNOTES:

The degree of pressure which they undergo must be taken into account. E.

From what has been premised, it follows, that our atmosphere is composed of a mixture of every substance capable of retaining the gasseous or a?riform state in the common temperature, and under the usual pressure which it experiences. These fluids constitute a mass, in some measure homogeneous, extending from the surface of the earth to the greatest height hitherto attained, of which the density continually decreases in the inverse ratio of the superincumbent weight. But, as I have before observed, it is possible that this first stratum is surmounted by several others consisting of very different fluids.

Our business, in this place, is to endeavour to determine, by experiments, the nature of the elastic fluids which compose the inferior stratum of air which we inhabit. Modern chemistry has made great advances in this research; and it will appear by the following details that the analysis of atmospherical air has been more rigorously determined than that of any other substance of the class. Chemistry affords two general methods of determining the constituent principles of bodies, the method of analysis, and that of synthesis. When, for instance, by combining water with alkohol, we form the species of liquor called, in commercial language, brandy or spirit of wine, we certainly have a right to conclude, that brandy, or spirit of wine, is composed of alkohol combined with water. We can produce the same result by the analytical method; and in general it ought to be considered as a principle in chemical science, never to rest satisfied without both these species of proofs.

We have this advantage in the analysis of atmospherical air, being able both to decompound it, and to form it a new in the most satisfactory manner. I shall, however, at present confine myself to recount such experiments as are most conclusive upon this head; and I may consider most of these as my own, having either first invented them, or having repeated those of others, with the intention of analysing atmospherical air, in perfectly new points of view.

I was obliged to repeat this experiment several times, as it is difficult in one experiment both to preserve the whole air upon which we operate, and to collect the whole of the red particles, or calx of mercury, which is formed during the calcination. It will often happen in the sequel, that I shall, in this manner, give in one detail the results of two or three experiments of the same nature.

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