\0$ ON ATMOSPHERICAL AIA. 



grains, according to Mr. Kir wan. Alfo let the charadlers 

 zv, T, and y, exprefs refpedively the cubic inches of the caiv 

 bonic acid, the oxigenous, and azotic gafes, which compofe 

 the mixture contained in 100 folid inches. Now w + j: -j-y 

 =;= 100 inches by hypothecs. But if 100 inches of air be de^ 

 i)oted by unity, the fame bulk of carbonic acid gas will be 

 exprelTed by the fraction -Jl^ff, by the experimental dala ; 

 confequently the weight of this gas in the mixture will be 

 found by the following proportion ; i, e. as 100 : 4-§^§ : : zv : 

 tV^%%^-* I" J'^^6 manner, the weight of the.oxigen is found 

 to be tVcV^* and th^t of the azote is t^tI^Io. Now the 

 fijra of thefe weights is equal to unity by the premifes of the 

 calculation ; if then the equation be multiplied by 100000 on 

 the common denominator of the unknown quantities, itaflumes 

 the following form ; i, e. 1 500 w -{-\\03 x -\~9S5 y= 1 00000. 

 Thus it appears that we have only two equations, when the 

 quantities to be determined are three ; this circumftance leaves 

 the problem unlimited ; that is, the value of one of the quan- 

 tities mull be difcovered without the aid of calculation. 

 Air contains car- M. Chaplal takes no notice of the carbonic acid in his ob- 

 bonic acid. fervations on the conliitution of common air ; which appears 



to be an overfight, at lead in a general view of the fubjecl ; 

 for various procelles of nature as well as art conftantly dif- 

 charge this gafeous acid into the atmofphere, whe^e its pre- 

 fence is alfo indicated l)y quick -lime being CDnverf.ed into a 

 carbonate, when placed in open (ituations. Thefe fa6ts 

 amount to more than a probability, that the lower parts of the 

 atmofphere contain a flight admixture of the carbonic acid : 

 this fraall portion, however, was undoubtedly retained, in a 

 great meafure, by the azotic gas which Mr. |Cirwan ufed in 

 his experiments ; becaule he prepared it from common air, 

 which was confined over mercury, together with a pafte of 

 fulphur and the filings of iron. 

 u and j> deter- This fmgle confideration induces me to follow the example 

 mined. ^f jyj^ Chaptal in making w of no value; and the ftep may be 



taken with the greateft fecurity in the prefent inftance, be- 

 caufe it increafes the value of x, if it alter it at all ; that is, 

 the amount of the oxigenous gas, as found by calculation, will 

 exceed the truth, on the fuppofition that the carbonic acid 

 remained in the azotic gas, which Mr. Kirwan weighed. If^ 

 tlicn, w be put equal to nothing, the preceding. equations al' 



' ' ■ fume 



