60 Royal Society of Edinburgh. 



Murray was the hygrometrk and not comlined water of sal 

 ammoniac ; for, as the whole ponderable matter of the two con- 

 stituent gases is condensed into the salt, whatever water of com- 

 position mnrifitic acVl gas may be supposed to contain, has be- 

 come an indispensable constituent of the solid ; and can no more 

 be separated by mere heat than the combined water of concen- 

 trated oil of vitriol. Nay, supposing that by intense ignition we 

 should resolve the salt into its ultimate elementary gases, still the 

 water would remain latent in the resulting muriatic acid gas, as it 

 did before the union, even according to Dr. Murray's own views. 



Dr. Ure is still inclined to consider his original experiments 

 on dry sal ammoniac, of which a notice was published in this 

 Magazine four months ago, as most decisive. 



Jan. 12, 1818. The continuation of Dr. Murray's Paper on 

 Muriatic Acid was read. In the preceding part of it the results 

 of experiments had been stated, whence it appeared that from 

 the action of metals on muriatic acid gas water is deposited This 

 is a result obviously incompatible with the doctrine in which 

 chlorine is considered as a simple sni)stance, since, according to 

 that doctrine, muriatic acid gas is the real acid, altogether free 

 from water. As the opposite doctrine holds the existence of com- 

 bined water in the gas to the amount of a fourth of its weight, a 

 portion of this may be supposed to be liberated by the action of 

 the metal. A difficulty however presents itself even on this view 

 of the subject. The action consists in the acid enabling the metal 

 to decompose the water and combine with its oxygen ; with the 

 oxide thus formed the acid unites, and no water remains to be 

 deposited, since none is liberated from its combination with the 

 acid, but what is spent in the oxidation of the metal. The pro- 

 ducts therefore ought to be the same on this hypothesis as on the 

 other, namely, a dry muriate or chloride, and hydrogen gas. 



It was shown that the water obtained in the experiments 

 could not be derived from hygrometric vapour ; that it could not 

 be accounted for from the supposition of a portion of water being 

 combined with the acid in the gas beyond that which is strictly 

 essential to its constitution ; — and that it could not be ascribed 

 to any lower degree of oxidation of the metal being established. 

 One explanation remained, that it might arise from the forma- 

 tion of a super-muriate, the quantity of water combined with the 

 quantity of acid, which forms a ngutral muriate, being sufficient 

 for the oxidation of the metal ; so that if an additional portion 

 of acid entered into the combination, the water of this might be 

 liberated. It was accordingly found that the products in ail 

 these cases were sensibly acidj and this even when any source of 

 fallacy, from a subversion of the combination by the agency of 

 water, was obviated. In the sequel another explanation was sug- 

 gested 



