fcOM«USTtdN 6F CHARfcoAt; 309 



quantity of oxigen consumed, supposing the carbonic acid 

 gas to contain its own bulk of oxigen gas. 



The purest charcoal I have burned, next to plumbago, is Charcoal of es- 

 tbat produced by decomposing the essential oil of rosemary gealial ° a » 

 in a red-hot tube. Probably other oils of the like kind 

 would furnish a similar charcoal. In its combustion it did 

 not form any notable quantity 6f water ! but it gave out 

 some oxicarburetted hidrogen, though in too small a quan- 

 tity, for the composition of the acid gas to be sensibly mo- 

 dified by it. From this experiment I found, that 100 parts 

 of carbonic acid contain 27*11 of carbon* and 72*89 of 

 oxigen. 



The combustion of anthracite, previously exposed to a Stone coal, 

 red heat, furnished too perceptible a quantity of water and 

 of hidrogen, for the results of this process to be calculated 

 with accuracy, and compared with the preceding. 



The combustion of box charcoal too, dried by long in- Box charcoal, 

 candescence, furnished an appreciable quantity of water and 

 oxicarburetted hidrogen. 



The combustion of charcoal, that had served for the pre- Charcoal used 

 paration of liquid hidroguretted sulphur, produced very l^qJidTulphur- 

 nearly the same quantity of water and hidrogen, as was ob- etted hidrogen. 

 tained from dried charcoal, that had not been exposed to 

 the action of sulphur. Hence we may infer, that this sub- 

 stance does not take from charcoal the hidrogen it contains. 

 It is probable, that sulphur contains either water Or its ele- Sulphur con- 

 ments; and that charcoal occasions the sulphur to become hidrogen? 

 hidroguretted by attracting the oxigen. The recent expe- 

 riments of Mr. Davy on sulphur by means of Voltaic elec- 

 tricity leave no doubt, that this substance contains a pretty 

 considerable quantity of oxigen and hidrogen. 



In these experiments where I burned charcoals containing Increase or di« 

 hidrogen, the gas, in which the combustion was effected, was "» inut,on °* 

 sometimes a little increased, at others a little diminished in 

 bulk. This difference appeared to me, to depend chiefly 

 on the more or less perfect combustion of the hidrogen 

 evolved. This combustion was more or less complete, not 

 only according to the proportion of circumambient oxigen 

 gas, but to the intensity of the heat, which in my experiments 

 varied, 



xr. 



