COMBUSTION OF CHARCOAL AND OF HIDROGEN* 173 



experiment, bat did not observe the precipitation*. I have 

 fumnd, however, that these opposite results may be recon- 

 ciled in some degree, by attending to the proportions of the 

 oxigen and hidrogen gas. If these gasses be mixed in such This depends 



proportion, that the hidrogen predominates after the com- °. n d»«prop«r~ 

 f . . t . - , , , tkm« of the 



bustion, scarcely any acid gas is formed, because the greater gas«?. 



part of the carbon remains dissolved in the hidrogen gas 

 unhurried; and the latter is proportionally more oxicarbu- 

 retted, than it was before the detonation. But when the 

 combustion is effected with excess of oxigen gas, almost all 

 the oxicarbu retted hidrogen is burnt, and a sensible quan- 

 tity of acid gas is obtained. Thus when 1 detonated 1000 

 parts of the purest hidrogen gas with 1000 of oxigen, I ob- 

 tained at least 3 parts of carbonic acid : but I obtained only 

 one part of this acid, when I detonated 1500 parts of the 

 tame hidrogen with 500 parts of oxigen. In the latter case 

 the superfluous hidrogen wa«t found to have a larger pro- 

 portion of carbon in an equal volume, than before the deto- 

 nation. 



These results are interesting, as they prove, that we do Pure hidroje* 

 not yet know the density of pure hidrogen gas, and that f as not J* 1 

 what we consider as such always contains a small proportion 

 of carbon, and probably of oxigen ; since Mr. Berthollet 

 has found, that no pure carbu retted hidrogen gas exists, 

 those so considered always containing some oxigen f. It 

 may even be questioned, whether carbon and oxigen be not 

 essential to the constitution of the substance which we have ^ 

 improperly termed pure hidrogen gas. These results too in- Carbon in de- 

 dicate, that the purest distilled water contains carbon; and j n •^JJJJj, 

 that the same may be said of ammonia, though the carbon 

 is in very small proportion, and perhaps accidentally pre- 



* At that time it w» not doubted, that the precipitation observed 

 was owing to the impurity of the metals, vrhich had been used for pro- 

 curing the hidrogen. Hence the existence df charcoal in zinc was ad- 

 mitted. Proust however could find no carbon in the black residuum left 

 by this metal after its dissolution in acids. To me it appears very pro- 

 bable, that the carbon of the hidrogsn gas evolved by zinc, as ntll m 

 by sevaral other metals, is to b« ascribed in part to the water decom- 

 posed. 



f Men* de la Societe d*Arcueil, torn. II, 



sent 



