188 ON T1IE WATER IN MURIATE OF AMMONIA. 



still lower than this, it is possible, that there may b 

 no apparent production of water. If the salt too has any 

 power of absorbing water, inferior even to what these 

 gentlemen sunpose, it is evident, that the portion of it in 

 s the upper part ;md curvature of the neck of the retort must 

 absorb the small portion of water, that may be volatilized 

 and ought, on by a moderate heat applied to the salt at the bottom, or 

 crole °tb pre- " "*? *^ e body of the retort; and according therefore to the 

 vent the ap. assumption they themselves maintain, no water ought to 

 pearanceof gppejar in this mode of making the' experiment, even 

 Otliei objec- though the salt may contain it. Farther, if any pressure 

 tions to their is present in consequence of ihe arrangement by which the 

 experiment. ^ j g exc i uf ] e d, (and Mr. Davy's experiment is not suffici- 

 ently described, to enable us to determine whether this were 

 the case or not,) this must retard or prevent the separation 

 of the water. And lastly, when the air is excluded, that 

 agency of it by which it promotes the transition of every sub- 

 stance into vapour by heat, lately so well illustrated by Gay- 

 Lussac*, is prevented from operating; and the same result 

 with regard to the expulsion of water in vapour from any 

 matter containing it cannot be obtained, as when a commu- 

 nication with the atmosphere is preserved. It was to ob- 

 viate some of these circumstances, that I performed the ex- 

 periment in the manner in which it was originally executed. 

 All of them however are neglected by Messrs. Davies, though 

 it is obvious, that their influence must be important; and 

 to account for the result they are said to have obtained, the 

 supposition is introduced of the salt attracting water from 

 the atmosphere, without any experimental evidence being 

 given, that it has any such power. 

 The cause I was satisfied prior to any experimental investigation, that 



they assume thecause thus hypothetically assigned is altogether fallacious. 



tor the appear- J r j -a o 



ance of water When asolublesubstance attracts water from the atmosphere, 

 fallacious. ^ con tinues to attract it, until it becomes humid, and is at 

 length dissolved. This is the case with potash, muriate of 

 lime, acetate of potash, and indeed every salt known to ab- 

 sorb water from the air ; and it follows from the very property 

 itself. The deliquescent substance imbibes water in conse- 

 quence of the strong attraction it has to it; and this attrac- 

 tion must continue to operate, until an equilibrium between 



* Rletfroires D , Arcueil 3 tonii 1, p. 204. it 



