ISIS.] Royal Society of Edinburgh. 147 



muriate of ammonia by heat, employing an apparatus somewhat 

 on the principle of Dr. Wollaston's cryophorus, and with u 

 successful result. He then submitted muriatic acid gas to expe- 

 riment hi various modes. Iron filings, perfectly dry and clean, 

 having been put into a glass tube surrounded with sand, and 

 placed across a furnace so as to be raised to a red heat, muriatic 

 acid gas, extricated from a mixture of supersulphate of potash 

 and muriate of soda, and conveyed through a tube containing 

 dry muriate of lime, adapted to the other, was transmitted over 

 the ignited iron. Moisture immediately appeared in the tube 

 beyond the ignited space, and soon collected in globules, and 

 hydrogen gas was disengaged. In another experiment the gas 

 was previously kept in contact with muriate of lime for two days, 

 and was then passed by a tube and stop-cock from the jar over 

 the ignited metal with a similar result. And in another form of 

 apparatus, still better adapted to afford a perfect result, and to 

 obviate any fallacy from the presence of aqueous vapour, 

 muriatic acid gas was conveyed from a jar, in which it had been 

 exposed to dry muriate of lime, through a bent tube into a tubu- 

 lated retort containing dry zinc filings ; heat was applied by a 

 lamp to favour the action of the metal on the gas ; moisture 

 condensed in the curvature and tube of the retort, and hydrogen 

 gas was collected at the extremity, which terminated under 

 mercury. The heat was renewed at intervals for three or four 

 days, with the requisite addition of fresh quantities of the mu- 

 riatic acid gas, and the production of moisture increased, until a 

 very sensible quantity of water was obtained at the end of the 

 experiment. 



Jan. 5. — The continuation of Dr. Murray's paper on Mu- 

 riatic Acid Gas was read. In the preceding part of it, it had 

 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 sub- 

 stance, since, according to that doctrine, muriatic gas is the 

 real acid altogether free from water. The opposite doctrine 

 holding the existence of combined water in the gas to the amount 

 of a fourth of its weight, a portion of it may be supposed to be 

 liberated by the action of the metal. A difficulty, however, pre- 

 I - itself even on this view of the subject. The action consists 

 in the acid enabling the metal to decompose the water, and 

 iliine with its oxygen. With the oxide thus formed the acid 

 r -, 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 products, therefore, ought to 

 bfl tin; same on this hypothesis as on the other, namely, a dry 

 muriate or cfctoride, and hydrogen gas. 



It v. i limn that the water obtained in the experiments 

 could nwi be thrived from hvjTometric vapour ; that it could not 



k 2 



