Acids, Alkalis, and their Compounds. 1 93 



if the whole water essential to the acid is decomposed by the ac- 

 tion of the metal, half the volume of hydrogen ought to be ob- 

 tained, muriatic acid gas being composed of equal volumes of 

 oxymuriatic gas and hydrogen gas ; while on the other hand, if 

 any additional portion of acid enter into union, besides that form- 

 ing a neutral compound, the water of this will be liberated, and 

 of course the full proportion of hydrogen will not be obtained. 

 I therefore endeavoured to determine whether this is the case or 

 not ; and in repeated experiments, in which iron and zinc acted 

 on muriatic acid gas, the quantity of hydrogen was always less 

 than the half; and on an average, about twelve measures were 

 obtained when thirty measures had been consumed*. It appears, 

 therefore, that in experiments attended with the results I had 

 obtained, that is, when a portion of water is obtained from the 

 action of metals on muriatic acid gas, and a super-muriate is 

 formed, the quantity of hydrogen evolved is not equal to half the 

 volume of the gas consumed ; and hence, in reference to these 

 experiments at least. Sir H. Davy's attempt to decompose chlo- 

 rine was very unnecessary, and the want of success, which it was 

 easy to anticipate, affords no argument whatever. 



Muriate of ammonia, it is stated, is not altered by being passed 

 through porcelain or glass tubes heated to redness; but if metals 

 be present, it affords similar results to muriatic acid gas, and the 

 water obtained is ascribed to the action of the hydrogen liberated 

 from the acid and from the ammonia on the oxide of lead in the 

 glass. In the ex]5eriments of which I have given an account 

 (Edinburgh Transactions, vol. viii. p. 301) I found that exposure 

 to a heat not so high as that of ignition is not necessary to ob- 

 tain water from the action of metals or muriate of ammonia; one 

 much more moderate, and at which no action on the glass can be 

 supposed to be exerted, is sufficient; and accordingly, not the 

 slightest indication of the glass being acted on can be perceived. 

 In obtaining, for example, water from a mixture of tin filings and 

 muriate of ammonia heated in a retort by the gentle heat of a 

 small lamp, the retort remains perfectly unaltered, in colour, 

 transparency, and lustre. 



These objections, then, I regard as of no force; at the same 

 time I do not consider the discussion as of much importance. 

 The view which I have now proposed of the nature of muriatic 

 acid does not rest on any exclusive proof of water being obtained 

 from it, but on other grounds; and it is quite sufficient that it 

 yields water in the same cases of chemical action, in which other 

 powerful acids, as the sulphuric, nitric and oxalic, afford it, while 

 the sulphurous and carbonic afford none. The same theory ap- 

 j)lied to the constitution of the former will fall with every proba- 



• Transactions of the Uoyal Society of Edinhtirirli, vol. viii. p. .'JOJ. 



Vol.54. No. 2r.7. Sept. 1819. N bility 



