ON THE NATURE OF OXIMURIATIC ACID. 135 



acid, water is aUvays present, and muriatic acid is formed ; 

 and as oximuriatie acid, he adds, is converted into muriiatic 

 acid g;is by combining with hidrogen, it is scarcely possible 

 to Hvoid the conclnsion, that the oxigen is derived from the 

 decomposition of wt\ter. Such facts however admit equally 

 of explanation on the supposition, that the oxigen is derived 

 from thedecomposition of the oximuriatie acid,butthat water 

 18 necessary to aid this decomposition by the affinity it exerts 

 to the muriatic acid. They are not therefore of themselves 

 more favourable to the one hypothesis than to the other. 



When muriatic acid gas is acted on by metals, the acid or the action of 

 disappears, and hidrogen gas is produced. In these cases '^*^^'* ^^^ "^"7 

 Mr. Davy supposes, that the muriatic acid is decomposed, 

 its oximuriatie acid combines with the metal, and its hidro- 

 gen is evolved, and accordingly the compounds formed dre 

 the same he remarks as those produced by the direct action 

 of oximuriatie acid on the same metals. But this explana- 

 tion rests on the previous assumption of the truth of the 

 theory, and the phenomena are equally explained by sup- 

 posing the hidrogen to be derived from the decomposition 

 of the portion of water combined with the acid in its gase- 

 ous state, the oxigen of this water combining with the me- 

 tal, and the oxide thus formed uniting with the real acid.. 

 It is true, that this production of hidrogen takes place even 

 when the muriatic acid gas has been previously exposed to 

 substances having a strong attraction to water, so as to 

 bring it to its driest state; but the same explanation m4jy 

 still be given, for when the acid is in this state it can only 

 be affirmed, that a portion of water has been abstracted 

 from it, not that the whole has been withdrawn. As the 

 water is removed from the acid gas, the affinity by which 

 the remaining quantity is retained must progressively in- 

 crease in strength, until it equal or exceed that of the sub- 

 stance attracting it; when of course its abstraction must 

 cease. The phenomena then afford no decisive proof of 

 IVJr. Davy's hypothesis, for before the explanation givert of 

 them in conformity to that hypothesis can be received as 

 exclusively just, it must be established by prior and inde- 

 pendent evidence, either that muriatic acid does not contain 

 combined water, or that it is a compound of oximurititic acid 

 and hidrotjen. If 



