Part 2 (1/2)

CHAP II

_General Views relative to the Formation and Composition of our Atmosphere_

These viehich I have taken of the forht upon the original formation of the atmospheres of the planets, and particularly that of our earth We readily conceive, that itsubstances: _First_, Of all bodies that are susceptible of evaporation, or,the state of aeriform elasticity in the temperature of our atmosphere, and under a pressure equal to that of a coluht inches of quicksilver in the barometer; and, _secondly_, Of all substances, whether liquid or solid, which are capable of being dissolved by this asses

The better to deter to this subject, which has not hitherto been sufficiently considered, let us, for a e would take place in the various substances which compose our earth, if its temperature were suddenly altered If, for instance, ere suddenly transported into the region of the planet Mercury, where probably the co water, the water of the earth, and all the other fluids which are susceptible of the gasseous state, at a te water, even quicksilver itself, would becoed into perasses, which would becoasses would , and certain reciprocal decompositions and new combinations would take place, until such ti aasseous substances had operated fully; after which, the ele 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 atree of pressure tends, in some measure, to prevent evaporation, and as even the h te, if prevented by a proportionally stronger co able to sustain a red heat in Papin's digester; we must admit, that the new atht, 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 saravity of the atmosphere would find certain liht even extend these reflections greatly farther, and exaht be produced in such situations upon stones, salts, and the greater part of the fusible substances which compose the ed into fluids, &c: But these speculations carry me from my object, to which I hasten to return

By a contrary supposition to the one we have been for, if the earth were suddenly transported into a very cold region, the water which at present coreater number of the fluids we are acquainted with, would be converted into solid eneous, like rock crystal, but which, in tieneous substances, would become opake stones of various colours

In this case, the air, or at least some part of the aeriform fluids which now compose the mass of our atmosphere, would doubtless lose its elasticity for want of a sufficient temperature to retain them in that state: They would return to the liquid state of existence, and new liquids would be formed, of whose properties we cannot, at present, form the ive a distinct proof of the following corollaries: _First_, That _solidity_, _liquidity_, and _aeriform elasticity_, are only three different states of existence of the same matter, or three particular modifications which al successively, and which solely depend upon the degree of temperature to which they are exposed; or, in other words, upon the quantity of caloric hich they are penetrated[8] _2dly_, That it is extre in a state of vapour; or, as we may better express it, that our atmosphere is a compound of all the fluids which are susceptible of the vaporous or permanently elastic state, in the usual temperature, and under the common pressure _3dly_, That it is not impossible we may discover, in our atmosphere, certain substances naturally very compact, even metals themselves; as a metallic substance, for instance, only a little ht exist in that situation

Ast the fluids hich we are acquainted, so with each other in all proportions; whereas others, on the contrary, as quicksilver, water, and oil, can only forether, separate and arrange the 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 difficultlyfroeneral ather regions, and form strata that float upon the coneous 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:

[8] The degree of pressure which they undergo must be taken into account E

CHAP III

_analysis of Atmospheric Air, and its Division into two Elastic Fluids; the one fit for Respiration, the other incapable of being respired_

From what has been premised, it follows, that our atmosphere is co the gasseous or aeriform state in the common temperature, and under the usual pressure which it experiences These fluids constitute afroht hitherto attained, of which the density continually decreases in the inverse ratio of the superincuht But, as I have before observed, it is possible that this first stratu 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 stratureat advances in this research; and it will appear by the following details that the analysis of atorously determined than that of any other substance of the class Che the constituent principles of bodies, the method of analysis, and that of synthesis When, for instance, by co water with alkohol, we fore, brandy or spirit of wine, we certainly have a right to conclude, that brandy, or spirit of wine, is composed of alkohol combined ater We can produce the saht 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 at 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 Ieither first invented the repeated those of others, with the intention of analysing atmospherical air, in perfectly new points of view

I took a14 plate II) of about 36 cubical inches capacity, having a long neck B C D E, of six or seven lines internal dia 2 so as to allow of its being placed in the furnace M M N N, in such a ht be inserted under a bell-glass F G, placed in a trough of quicksilver R R S S; I introduced four ounces of pure mercury into the matrass, and, by means of a syphon, exhausted the air in the receiver F G, so as to raise the quicksilver to L L, and I carefullyon a slip of paper Having accurately noted the height of the therhted a fire in the furnace M M N N, which I kept up al twelve days, so as to keep the quicksilver always al reh not boiling, was continually evaporating, and covered the interior surface of the vessels with s to a sufficient size, fell back into the mass at the bottoan to appear on the surface of the radually increased in size and number; after which they ceased to increase in either respect

At the end of twelve days, seeing that the calcination of the uished the fire, and allowed the vessels to cool The bulk of air in the body and neck of the lass, reduced to a medium of 28 inches of the barometer and 10 (545) of the thermometer, at the commencement of the experiment was about 50 cubical inches At the end of the experi air, reduced to the same medium pressure and temperature, was only between 42 and 43 cubical inches; consequently it had lost about 1/6 of its bulk Afterwards, having collected all the red particles, for rains

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 ofthe calcination It will often happen in the sequel, that I shall, in this ive in one detail the results of two or three experiments of the same nature

The air which remained after the calcination of the mercury in this experiment, and which was reduced to 5/6 of its forer fit either for respiration or for co introduced into it were suffocated in a few seconds, and when a taper was plunged into it, it was extinguished as if it had been irains of redthis experi a proper apparatus for receiving such liquid, or gasseous product, asapplied a fire to the retort in a furnace, I observed that, in proportion as the red an gradually to decrease in bulk, and in a few ether; at the sa mercury were collected in the recipient, and 7 or 8 cubical inches of elastic fluid, greatlyboth respiration and colass

A part of this air being put into a glass tube of about an inch dia properties: A taper burned in it with a dazzling splendour, and charcoal, instead of consu quietly as it does in co noise, like phosphorus, and threw out such a brilliant light that the eyes could hardly endure it This species of air was discovered almost at the same tiave it the naisticated air_, Mr Scheele called it _ehly respirable air_, to which has since been substituted the terht to think of these deno upon the circumstances of this experi its calcination, absorbs the salubrious and respirable part of the air, or, to speak more strictly, the base of this respirable part; that the re combustion or respiration; and consequently that atmospheric air is composed of two elastic fluids of different and opposite qualities As a proof of this important truth, if we recombine these two elastic fluids, which we have separately obtained in the above experiment, viz the 42 cubical inches of mephitis, with the 8 cubical inches of respirable air, we reproduce an air precisely si nearly the sa co to the calcination of h this experi the two principal elastic fluids which compose our ative us an exact idea of the proportion in which these two enter into its composition: For the attraction of mercury to the respirable part of the air, or rather to its base, is not sufficiently strong to overcome all the circumstances which oppose this union These obstacles are the mutual adhesion of the two constituent parts of the atmosphere for each other, and the elective attraction which unites the base of vital air with caloric; in consequence of these, when the calcination ends, or is at least carried as far as is possible, in a determinate quantity of atmospheric air, there still remains a portion of respirable air united to the mephitis, which the mercury cannot separate I shall afterwards show, that, at least in our climate, the atmospheric air is composed of respirable and mephitic airs, in the proportion of 27 and 73; and I shall then discuss the causes of the uncertainty which still exists with respect to the exactness of that proportion