270 WATER IN ^VltTRIATlC ACID GAS. 



salt, as on the water combined with it, and their mutual affinity 

 must retain them in union till both are sublimed together. 

 If other salts which are fixed, and which have a less strong 

 attraction to water, yield it only at a high temperature, and then 

 imperfectly, it is absurd to imagine, that muriate of ammonia 

 should yield it at a much lower temperature, and yield it entirely. 

 The experiment, therefore, was designed rather to prove the ex- 

 istence of combined water in muriatic acid gas, and though (he 

 quantity obtained may not be the whole quantity which, from 

 other facts, there is reason to conclude, exists in the acid gas, it 

 establishes this as much as if a larger quantity were obtained. 

 It proves the The production of any water is incompatible with Sir Hum- 

 existence of phry's hypothesis, and, therefore, refutes it: it is conformable 

 water, and es- r , J r . ' . = ' ' . -i~, 



tablis-hes the to tne opposite doctrine, and becomes, therefore, a proof or its 



doctrine. truth; and for the quantity being less than that from other sa- 



line combinations of the acid, an adequate cause can be as- 

 signed. The actual result, indeed, is precisely that which is 

 to be expected, a sensible portion of water more considerable 

 as the experiment is performed in a manner more favourable 

 to its disengagement, but inferior to what is obtained from 

 "" other combinations of the acid, from which it is obvious, 

 a priori, that the water must be more easily expelled. 



So far I have restricted my observations chiefly to the re- 

 sult of the experiment of heating the salt in close vessels. A 

 point not less important, which remained for determination, 

 is that relating to the result when it is heated in open vessels, 

 and to the supposed fallacy connected with this in the absorption 

 of water from the air. 



Whether the I had found that, in this mode of conducting the experi- 



ea!t absorbs ment, a very sensible quantity of water was obtained: and 



water from , . , . • , .. . , , . . , 



the air, as » this was not denied, but explicitly admitted, by my opponents. 



posed by Sir Mr. J. Davy, who had heated the salt in close vessels, without 

 I ' avy * obtaining water, found, that when he n followed Mr. Murray's 

 example, and collected the salt in the atmosphere, and intro- 

 duced it into another retort, on heat being applied, water, in 

 no inconsiderable quantity, was evolved, as he described." But 

 to account for this, without admitting the conclusion subver- 

 sive of his hypothesis, Sir Humphry Davy advanced the sup- 

 position, that the salt absorbs water from the air during its 



trans- 



