Experiments on Muriatie Acid Gas. 107 
lysis of hydrochloric acid ; or it might be derived from the com- 
bined water of muriatic acid, of which the oxygen became fixed 
in the muriate of tin. When chlorine also at high heats was 
made to act on earths or common metallic oxides, the evolved 
oxygen could be referred with equal probability either to the 
solid or to the gas. 
And though we ignite by the strongest Voltaic power, char- 
coal or other combustibles in chlorine, still we shall not be able 
to convert it into muriatic acid gas, for want of the essential 
constituent water; no more than we can, without the same 
water, obtain oil of vitriol. Present water to chlorine, then 
light alone will separate its oxygen, and leave muriatic acid. 
Such, indeed, is the affinity existing between the muriatic acid 
basis and water, that those muriates which of themselves resist 
decomposition at a red heat, when exposed at that temperature 
to the vapour of water, are speedily resolved into gaseous mu- 
riatic acid, and their peculiar bases. 
By restoring the theory of Lavoisier and Gerthollet, we a6 
tid of those mysterious and almost incomprehensible transfor- 
mations which a drop of water has been lately conceived to pro- 
duce on some of the muriates. Dried sea-salt, for example, 
when viewed as a compound of chlorine and ‘sédiumn, is no 
sooner moistened, than a portion of water resolves itself into 
oxygen and hydrogen; whence result soda and hydrochloric acid, 
and a solution of muriate of soda, Expel the drop of water, we 
_have a chloride of sodium once more ; and we may repeat this 
invisible change for an indefinite number of times by the addition 
or subtraction of a little moisture.° Thus we must consider dry 
salt and moist salt to be bodies widely and essentially different, 
the former containing neither alkali nor acid, while the latter 
contains both. This supposition, which the chloridic theory 
compels us to make, must surely be reckoned somewhat vio- 
lent. 
XVII. Experiments on Muriatic Acid Gas, with Observations 
on its Chemical Constitutton, and on some other Subjects of 
Chemical Theory. By Joun Murray, M.D. F.R.S. E. 
Fellow of the Royal College of Physicians of Edinburgh.* 
Somz years ago I proposed, as decisive of the question which 
has been the subject of controversy on the nature of oxymuriatic 
and muriatic acids, the experiment of procuring water from 
muriate of ammonia, formed by the combination of dry ammo- 
* From the Transactions of the Royal Society of Edinburgh. 
niacal 
