24? On the anjl'ituent Parts of Azof. 



analyfis of fixed alkalies, it has been effefted completely* 

 As I do not intend to enlarge on this fubje6l in the prcfent 

 memoir, I (hall only rjiention one of thofe experiments 

 which are conclufive. When alkali is fufed with filex for 

 the purpofe of making glafs, you analyfe the alkali. The 

 hydrogen efcapes under the form of a gas, and the oxygen 

 combines itfelf with the filex, glafs being nothing elfe but 

 an ojcyd of filex. Too much oxygen, however, muft not 

 enter into the compofition, as it would render it lefs tranfpa- 

 rent : this is the reafon why glafs-makers add fubftances 

 greedy of oxygen, as manganefe. 



Having communicated to M. Mayer the refult of my ex- 

 periments, by which I lb e,vidently confirmed an idea thrown 

 out by him at hazard, and of which he has the merit of 

 being the author, this learned philofopher lent me a fliort 

 iuemoir, of which the following is an extraft : — " I am in- 

 clined to believe," fiiys he, " with Mr. De Luc, that the 

 evaporation of w ater, fuch as eflbtilcd by nature on a large 

 fcale, is a real converfion of water into air. It is indeed true, 

 that we have never yet been able iu our laboratories to convert 

 water into air by evaporation ; but the reafon of this is, that 

 we are unacquainted with the part which both light and 

 eleilricity perform in evaporation in general. It appears to 

 jrne probable, however^ that the ponderable parts of atmo- 

 fpheric air, that is to fay, oxygen and azot, have no other 

 iourcc than from the water with which the furface of our 

 ^lobe is covered. The very fmall quantity of oxygen gas 

 which vegetables exhale by the influence of the folar light, 

 ;is far from being able to make good the enormous confump- 

 ,tion of oxygen which daily takes place in our atmofphere fo 

 .many dlfl'erent ways: but by fuppofing, according to this the- 

 ;orv, that xoo grains of water arc converted by the fecret procefs 

 of nature into lOO gi'ains of atmofpheric air, that is to fay, into 

 a chemical mixture of oxygen and hydrogen, we may find, by 

 .a very fimple calculation, in what proportion the oxygen and 

 ^hydrogen combine to form the azot which we find in the at- 

 mofphere. We muft, however, keep in view, that what we 

 call azot is not always of the iame nature, and that there i* 



coufiderable 



