Experiments .on Charcoal* 7 1 



meried in a mixture of ice and marine fait kept conftantly at 

 7 or 8 degrees below zero of the centigrade thermometer. To 

 one of them was adapted an empty bladder, and to the other 

 a fecond containing 12 litres of oxygen. 



The great tube being heated, at the place where the char- 

 coal was the gas was made to pafs ; and, when the combuf- 

 tion was completed, a (ingle atom of water was not dcpofited. 

 The tube containing the muriate of lime, which had traverfed 

 the oxygen before it was employed, having been weighed, 

 was found to be increafed 0*13 grammes ; that is, 0*02 more 

 than it ought to have been according to the above table of 

 deficcations ; which arofe from the cold experienced by the 

 gas. The muriate of lime traverfed by the product of the 

 combuftion, which ought to have contained water, wasjiot 

 increafed more than 0*02 grammes. This was (till owing 

 to the moifture taken by the charcoal from the atmofphere 

 at ithe time of its introduction into the tube. But, if we 

 mould choofe to believe that this quantity was produced by 

 the combuftion, as It contained only 0*003 grammes of hy- 

 drogen, arifing from 4-50 grammes of charcoal, there would 

 txift in 100 grammes but 0*065 grammes; that is to fay, 

 ttVo> a quantity inappreciable. 



C. Berthollet, in a letter printed in the Bibliotheque Bri- 

 tanmque* , , fixes at 0.0902 grammes, or 1*7 grain, the hydro- 

 gen contained in 1*9683 litres, or 100 cubic inches of in- 

 flammable gas, arifing from the reduction of the oxide of 

 zinc by charcoal. But this quantity of gafeous oxide of car- 

 bon weighs nearly 2*278 grammes, and contains 1*139 gram- 

 mes of charcoal, and as much oxygen. This charcoal ought 

 to contain, therefore, the 0*0902 grammes of hydrogen; that 

 is to fay, in 100 parts there ought to be 7*91 of hydrogen. 

 C. Berthollet, then, has fixed higher than is indicated by ex- 

 periment the quantity of hvdroii;en contained in carbonic acid 

 gas, and consequently in. charcoal. We have, indeed, feen 

 that we can fuppofe in the latter body at moll 0065 per cent. 

 This experiment, made with the greateft exactnefs poflible, 

 $ill proves that 100 parts of carbonic acid confift nearly of 

 28 parts of carbon and 72 of oxvgen — a refult given by the 

 celebrated Lavoifier; and if he obtained water in that com- 

 buftion, it ought not to occafion any error in the fractions of 

 the refult, its exiftence being, as we have already laid, an- 

 terior to the act of combuftion. 



Being defirous to know whether all kinds of charcoal, like 

 that of wood, might be freed bv fire from all the hydrogen 

 combined with them, we found that the charcoal of fugar, 

 1 * No. 141. 



E 4 . wax, 



