MURIATIC AND OXYMURIATIC ACID5. 43 



repeat the principal experiments described in my memoir, but 

 to institute others, with the advantage of a more perfect appa- 

 ratus than I then possessed, and of greater experience in the 

 management of these delicate processes. 



This repetition of my former labours has discovered to me Uncertainty of 



an instance in which I have failed in drawing the proper con- an ex penment 



b ' l . of the quantity 



elusion from facts. In two comparative experiments on the of hydrng. 



electrization of equal quantities of muriatic acid gas, the one evolved from 



, i , • • i' iii • mur. ac. gas 



ot which was dried by muriate of lime, and the other was in dr j e( j and not 



its natural state, I found a difference of not more than one per dried. 

 cent, in the hydrogen evolved, relatively to the original bulk 

 of the gas*. Yet, notwithstanding these results, I have ex- 

 pressed myself iricfined to believe, that some water is abstracted 

 by that deliquescent salt ; and this belief was confirmed, seve- 

 ral years afterwards, by the event of an experiment in which 

 muriatic acid gas, dried by muriate of lime, gave only Jj. 

 hs bulk of hydrogenf, a proportion much below the usual ave- 

 rage. The question, however, was too interesting to be left 

 in any degree of uncertainty j and I have, therefore, made 

 several fresh experiments with a view to its decision, in 

 the course of these I have found, that though differences in 

 the results are . produced by causes apparently trivial, some 

 of which I shall afterwards point out, yet that under equal The quant j tv 

 circumstances, precisely the same relative proportion of hy- is the same, 



drogen gas is obtained from muriatic acid gas, whether ex- w ie P^ lte . 

 & => ° muriatic acid 



posed or not to muriate of lime ; and that its greatest amount gas be exposed 



does not exceed J r or V-tj the original volume of the acid gas. °. r not *° ' 111U " 

 1 b ' 4 ° ° nate of lime. 



In the paper last quoted* Itiave also described an experi- 



• i , -, , , i , , , • • • Muriate of 



ment, in which sensible heat was evolved by bringing muriate ij me does not 



of lime into contact with muriatic acid gas ; a fact which, if unless humid, 

 established, would go far to. prove the existence of water in w ; tn muriatic 

 that gas. But on repeating the experiment with muriate of acid gas. 

 lime recently cooled from fusion, and over mercury carefully 

 deprived of all moisture by boiling, I was not able to discover 

 any increase of temperature, though a very sensible air ther- 

 mometer was inclosed in the vessel containing the gas. The 

 evolution of heat takes place, only when 4he muriate of lime 



* Page 191. f Phil. Trans. 1809, page 433. 



} Page 433, note. 



hat 





