37« Pretended Compofition ef Azete. 



After all thefe dlfcuflions, Girtanner fupports the new ideas which he prefents in his 

 memoir, upon feveral fails, for the moft part borrowed, and already accurately difcufled, 

 amongft which, the following muft be confidered as fundamental. " "When water is boiled 

 " in a retort of glafs, or other material, azote gas is obtained." The author prefcribes 

 thefe precautions : " In order to obtain azote gas in the greateft quantity, the water muft 

 " evaporate flowly, and over a very gentle fire, which muft not be raifed." 



" It is invariably obferved in all thefe experiments, that when the laft drop of water 

 " evaporates, the azote gas is no longer produced, though the heat be kept up." 



An aflertion fo poQtive engaged me to repeat the experiment, with the precautions pre- 

 fcribed by Girtanner. It was made with water newly diftilled, and with the well wafhed 

 precipitate of alum by pot-afh. It was likewife made with a very white clay, with which I 

 was fupplied by Cit. Guyton ; but though the quantity of water was confiderable, and, con- 

 fequently, thefe two experiments were of long duration, no gas became difengaged, and 

 the refult was the fame as that of the Dutch chemifts. 



It is, neverthelefs, upon this faft, which is fo eafy to be repeated, that Girtanner prin- 

 cipally eftabllfhes the compofition of azote, and thence that of the atmofphere, " which 

 " is not, as till now has been imagined, a mixture of oxygen gas and azote gas, but rather 

 " a mixture of oxygen gas and hydrogen — water in the form of gas, if I may be allowed 

 " to make ufe of fuch an expreflion. When, by thofe chemical experiments which very 

 " improperly have been called eudiometrical, the oxygen is feparated from the hydrogen, 

 *' this feparation can never be entirely or completely made; a part of the oxygen remains 

 *' united to the hydrogen, and forms the chemical combination which we call azote, and 

 " which we obtain in thefe experiments." 



So that when we make a mixture of oxygen and hydrogen gas, we form atmofpheric air, 

 and the differences of fpccific gravity and other properties in all our experiments, as well as 

 the produds of combuftion, are only flight circumftances, of which Girtanner takes 

 no account. 



The memoir of Girtanner induced Citizen Bouillon la Grange to make experiments 

 more numerous than mine, but which lead to the fame conclufions. I fliall here prefent a 

 fliort account of them, which he has kindly communicated to me. 



He did not obtain any azote gas by boiling diftilled water either alone, or with clay or 

 alumine in a glafs retort, to which he applied a tube of glafs or of porcelain. 



In like manner no difengagement of azote gas took place when the fame experiment was 

 made with filiceous earth obtained by fluoric acid. 



Having placed lime, obtained from white marble, in a tube of the fame kind, he pafled 

 the vapour of water through this tube, which had its extremity immerfed in lime water. 

 A fmall quantity of carbonic acid was difengaged, which formed carbonate of lime, but no 

 azote gas was produced. 



If, inftead of lime, clay is made ufe of with the fame apparatus, a little carbonate of lime 

 becomes formed, but there Is no difengagement of azote gas. 



3 If 



