1 ON MURIATIC ACID GAS, &C. 303 



But though I consider this conclusion as established, there 

 is a considerable difficulty attending the theory of the experi- 

 ment. The result of water being obtained is actually different 

 from what is to be looked for, on the doctrine of muriatic acid 

 gas containing combined water ; and even when the fact is 

 established, the theory of it is not easily assigned. On that 

 doctrine, it must be held that in the action of metals on muriatic 

 acid gas, the metal attracts oxygen from the water, the corre^ 

 sponding hydrogen is evolved, and the oxide formed combines 

 with the real acid. No water, therefore, ought to be deposi- 

 ted, for none is abstracted from the acid, but what is spent in 

 the oxidation of the metal.' This will be apparent, by attend*- 

 ing to the proportions in a single example, from the scale of 

 chemical equivalents : 100 grains of iron combine with 29 of 

 oxygen, and in this state of oxidation unite with 99 of real mu- 

 riatic acid. This quantity of acid exists in 131.8 of muriatic 

 acid gas, combined with 32.8 of water ; and this portion of wa- 

 ter contains 29 of oxygen with 3.8 of hydrogen. There is .pre- 

 sent, therefore, exactly the quantity of oxygen which the me- 

 tal requires to combine with the acid ; and no water remains 

 above this. Or it may be illustrated under another point of 

 view. Muriatic acid gas is composed of oxymuriatic gas and 

 hydrogen. A metal acting on it must attract the oxymuriatic 

 ncid, — that is, the muriatic acid and oxygen, and liberate the 

 hydrogen. No water, therefore, ought to appear, more, on 

 this theory, than on the other; but the real products in both 

 must be a dry muriate, or chloride, and hydrogen gas. In the 

 action of ignited metals on muriate of ammonia, it. is equally 

 evident, on the same principle, that no water ought to be ob- 

 tained. How, then, is the production of water to be accountr 

 ed for? 



- Though the water obtained in these experiments cannot be 

 derived from hygrometric vapour in the gas, there is another 



view 



