?50 Mem^r oa the Quatitiiy tf 



tingiufhj check, and - luibcate it in a moment; fuch ^ire 

 caloric and light, given 'prematurely to the germs of plants 

 and of animals. , 



Mutatd fratiguHti tjc^fneU donfiwaHt, Liiw. 



. fc . ... ■ ■ ' I .■ ■ 1 ^ 



V ' ' . I 3 n ► 'r ■■ ~-| ■ -; i ■ • - 



. .■ ■■ ■■' ■' :" ;■ -no V ■♦.•■' ■ 



XXXI. Memoir ott tbe Quantify of P'iMl^'Aif^ in the At mo- 

 fphere^ and the different Methods of meafuring it. By 

 M. Anthony de Marti^ Member of the Royal Aca- 

 demy of the Arts and Sciences at Barcelona, 



JL H E celebrated Hales obferved that common air, when 

 expofed with other fiibltances, was reduced to a fmaller vo- 

 hctnti '■ Dr* Prieftley advanced further in this matter^ having 

 difcoi'^Ttd by his experiments that nitrous gas caufes a dimi* 

 nation in air more confiderable according as it is more proper 

 for refpiration; and on the other hand, that inflammable air, 

 mephitic air, and other aeriform fluids incapable of main* 

 taining animal life, do not in the like manner diminiih ni-* 

 trous gas. Other philofophers afterwards obferved this di- 

 minution of air proportioned to its purity by means of hvef 

 of fulphur, apafte made of fulphur and filings of iron moifl- 

 ened with water, by the combuflion of inflammable air, and 

 by that of phofphorus. Thefe fubdances, which abforb the 

 refpirable air to the exclufion of other aeriform bodies which 

 may be mixed with it, have fervcd as the means of afcertain* 

 ing the purity of every kind of air whatever. Different kinds 

 of eudiometric proofs have been employed : ift^ That of ni- 

 trous gas : ad. That of fulphuret : 3d, That of a pafl;e of ful- 

 phur and iron : 4th, That of inflammable gas : 5th, That of 

 phofphorus. But have all thefe pioofs been carried to fuch 

 a degree of perfe6lion as to render them equally convenient 

 and correal? This examination will form the fubjeft of this 

 eflay, which will naturally lead me to the analyfis of atmo- 

 fpheric air* 



This air is conflantly found more or Icfs impregnated with 



different heterogeneous bodies, and particularly water, the 



^quantity of which M. De Saullure has (hown us a method 



• 4 of 



