EXPERIMENTS. ON MURIATIC ACID GAS. Jg5 



\bt cases of chemical action exerted by other acids, yet stitl, 

 .^ncea possible explanation may be given by the latter, the 

 question remains so far undecided. 



,. This observatioji applies to the experiments, from which instances of 

 it was inferred, that water exists in muriatic acid gas; ^^'^* 

 4hough at first view they appear to prove it, the proof must 

 be admitted to be doubtful, as they admit of explanatioa 

 on the opposite opinion. Thus the proof from the agency 

 of water in facilitating the expulsion of muriatic acid gas 

 from dry muriates is ambiguous, as the water may be sup- 

 posed to operate either by its affinity to the acid, or by af- 

 fording hidrogen to form it. The production of hidrogen, 

 when metals are acted on by muriatic acid gas, is a proof of 

 equal ambiguity; since it may be supposed to be derived 

 either from the decomposition of the acid, or of water exist- 

 ing in it. Even apparently the most conclusive of all these 

 facts,— the production of water, when muriatic acid gas is 

 acted on by substances with which acids in general com- 

 bine, as for example the metallic oxides, admits of this dou- 

 ble explanation. The acid is absorbed; and it might be 

 inferred, that it combines with the metallic oxide, while the 

 water which appears is deposited from the gas, in which it 

 had previously existed in a state of combination. But this 

 conclusion, though conformable to the most extensive and 

 strict analogy, is avoided on the opposite hypothesis of mu- 

 riatic acid gas being a compound of oximuriatic acid and 

 hidrogen, by the supposition, that the acid is decomposed, 

 that its hidrogen combines with the oxigen of the metallic 

 oxide, and forms this water, while the metal itself combines 

 with the oximuriatic acid. 



If we can procure however a substance not oxidated, and Only mode<^ 



yet capable of combining with muriatic acid, this source of ^T2^**'"^ *•* , 

 .... .,1,1 . difficulty. "'■■'■' 



ambiguity is avoided, and the experiment may be rendered 



conclusive. There is only one such substance— 'ammonia. 

 No oxigen can be detected in its composition, and Mr, 

 Davy himself admits, that it combines directly with muria- 

 tic acid, and does not decompose it. It cannot therefore 

 eause any formation of water. Neither can it be supposed 

 tb afford water J for, when dried by exposure to substances 

 having a strong affinity to water, it retains no sensible por- 

 tion; 



