384 SCIENTIFIC NEWS. 



pour ; while part of the hidrogen forms water, and another 

 part appears as pure hidrogen gas. 



Other acids. Sulphuric, phosphoric, and arsenic acid, equally de- 



compose this gas ; but the effect is produced very slowly, 

 and the arsenic is deposited for the most part in the me- 

 tallic form. In the decomposition of this gas by acids in 

 general, a very perceptible increase of volume takes place 

 at the commencement of the process. 



Add solutions Most of the solutions of the metals in acids likewise de- 

 compose it. The hidrogen is in part burned by the disoxi- 

 genation of the metallic oxide, and in many cases by the 

 disoxigenation of the acid likewise, with which the metal 

 was combined, and forms water, while another part is 

 converted into pure hidrogen gas. Thus the other com- 

 ponent part, the arsenic, is separated, and in most cases, 

 at least at the commencement, appears as a pure metal : 

 but in general, if the acid have a weak affinity for oxigen and 

 the oxide, or if the metal dissolved in it be highly oxided, the 

 arsenic is soon converted into oxide, and thence into ar- 



Corrosive mil- senious, or sometimes into arsenic acid. This is most 

 striking with the corrosive muriate of mercury, which in 

 this experiment is converted into mild muriate. This mc- 



tesSTofft la 'l' c sa ^ * s sucn a sensible test of arsenicated hidrogen gas, 



that it is capable of detecting it when mixed with ten thou- 

 sand times its bulk of atmospheric air, or of pure hidro- 

 gen, as was found by experiment. 



Kemarkable prof. Stromeyer concluded with a remarkable experi- 



pentine. ment, showing the effect of oil of turpentine on arseni- 



cated hidrogen gas, all the phenomena of which however 

 do not appear easily explicable. Ten cubic inches of the 

 gas being confined over this essential oil, all the arsenic was 

 separated in the course of ten hours, so as to leave the hi- 

 drogen gas pure. No perceptible deposition of metal or 

 oxide took place; but the oil appeared milky and viscous ; 

 and after some time small sixsided crystals, terminating in 

 pyramids, were found adhering to the sides of the vessel. 

 These crystals, being set on lire, burnt like oil of turpen- 

 tine, emitting at the same time a very distinguishable smell 

 of arsenious acid. A similar appearance took place on 

 transmitting arsenicated hidrogen gas through oil of tur- 

 pentine. 



riate of mer- 

 cury 



