COMBUSTION OF CHARCOAL AND OF HIDROGEN. l6 k 3 



gr.]. The globe weighs about a kilog. [2lbs. 3oz. avoid.], 

 and contains 5941*6 cub. centirn. [36-2 cub. inches.] 



I reduced the volume of gas to the pressure of 0*758 

 met. [29*82 in.], and the temperature to 12'5° [54*5° F.], 

 admitting with Gay Lussac, that air dilates TTr f n for each 

 degree. The temperature of melting ice, to which the vo- 

 lume of a gas is sometimes redu< ed, is so remote from those 

 at which the weighings were made, that, if there be a little 

 inaccuracv in our method of correction for each degree of 

 temperature, the errour must increase to a sensible quan- 

 tity, when the reduction is considerable. My experiments 

 appear to indicate generally, that, when a gas is weighed at 

 a temperature approaching that of melting ice, and the 

 usual calculations are made to reduce it to the mean tempe- 

 rature,* and the extreme humidity agreeable to this tempe- 

 rature, the gas, thus corrected, appears sensibly lighter, 

 than it is found to be by actual experiment at this mean 

 temperature. On the contrary, if a gas be weighed at a 

 temperature considerably above the mean, and reduced to 

 this mean by calculation, the corrected weight will come out 

 greater, than that obtained by direct experiment. Though 

 this result requires for its confirmation n greater number of 

 observations, it leads me £o think that we ought to avoid too 

 great corrections for temperature. 



The weight of oxigen and carbonic acid gasses are re- 

 duced to the term of extreme humidity, agreeable to the 

 mean temperature of 12-5° [64*5° F.], because we obtain 

 them nearly in this state. The specific gravity of aqueous 

 vapour, at temperatures very remote from the mean, has 

 not yet 'been determined in a manner sufficiently precise, to 

 allow us no room to apprehend errour in reducing it to the 

 ary state. 



Weight of a cubic decimetre [60*895 cub. in.] of. humid Weightof o*i. 

 oxigen gas, the thermometer at 12*5° [54*5° F.], and' baro- 

 meter at 0*758 of a metre [29*82 in.]. 



According to Lavoisier 1*3583 gram. 20*9725 grs. 



Seguin, Fourcroy 



and Vauqnelin • • >* 1 "3523 20*879^8 



Bioti- 1*3538 ( 20*903*0 



. my ©bservaiioa- 1*3563 ^>20*94l6 



* rt Mean , •• • 1*3552 80 9^42 



M2 The 



