ON MURIATIC ACID GAS, &C 301 



In all the preceding experiments, water has been procured 

 from muriatic acid gas. It is obvious, that such a result can- 

 not be accounted for on the hypothesis, that it is the real acid 

 free from water, a compound merely of chlorine and hydrogen. 

 On the opposite doctrine, as muriatic acid in its gaseous form 

 is held to contain water, it may be supposed to afford a portion 

 of it. 



It may be maintained, however, in this, as it was in the ex- 

 periment of obtaining water from the muriate of ammonia by 

 heat, that the water produced is derived from hygrometric va- 

 pour in the gas. To obviate this, it is sufficient to recur to 

 the fact established by ttie experiments of Henry and Gay 

 Lussac, that muriatic acid gas contains no hygrometric vapour; 

 and to the obvious result in the experiment, that no quantity 

 that can be assumed, would be adequate to account for the 

 quantity actually obtained. The circumstances of the experi- 

 ment, 



monia, and that this might afford an easy mode of exhibiting the results. I ac- 

 cordingly found, that on mixing different metals with sal ammoniac in powder,, 

 previously exposed to a subliming heat, and exposing the mixture to heat by a 

 lamp, so regulated as to be short of volatilization, the salt was decomposed, am- 

 moniacal gas was expelled, and moisture condensed in the neck of the retort ; 

 covering a space of several inches with small globules, and at length running 

 down. The metals I employed were iron, zinc, tin, and lead; 100, 150, or 200 

 grains of each metal, dry and warm, being mixed with 100 grains of the salt, 

 likewise newly heated. To obviate any fallacy from common sal ammoniac be- 

 ing employed, I repeated the experiment with the salt formed from the combina- 

 tion of its two constituent gases, and obtained the same result. But although 

 this affords an easy mode of exhibiting the production of water, it is not favour- 

 able to obtaining a perfect result, the heated ammoniacal gas carrying off a con- 

 siderable portion of the water deposited ; and accordingly, the quantity, instead 

 of increasing as the experiment proceeds, at length diminishes, and the ammoni- 

 acal gas deposites a portion of water in passing through mercury, or in being con- 

 veyed through a cold tube. 



