1^ On the Action of Chlorides and Water. [Jan. 



There is one case which I have aheady hinted at which 

 'M>pears to me difficult of explanation upon any supposition. 

 When chloride of mercury is put into water, as already noticed, 

 ^either solution nor action takes place : if we add potash to the 

 mixture, protoxide of mercury is immediately precipitated. Now 

 in this case it would certainly appear to be most probable that 

 ^he oxygen is suppHed by the potash, the chloride of potassium 

 formed remaining as such in solution. If, however, we substi- 

 tute ammonia for potash, still the decomposition is effected, 

 muriate of ammonia is formed, and protoxide of mercury pre- 

 cipitated. In this case it would seem that water is decom- 

 posed by the intervention of ammonia ; for not containing any 

 oxygen, it cannot yield it, as the potash may be supposed to do. 

 It is difficult, I think, to explain this action, and on this account 

 I am far from denying the possibility of tartaric acid to effect 

 that decomposition of water which may be supposed to occur 

 when it acts upon chlorine, potassium, and water. Certainly 

 what ammonia appears to do in the case of chloride of mercury, 

 tartaric acid may effect in that of chloride of potassium. 



In vol. vi. p. 185, of the AnyiahyM.. Gay-Lussac says, "When 

 a solution of chloruret of calcium (which he supposes to exist in 

 solution as such) is mixed with subcarbonate of ammonia, the 

 chlorine must pass to the state of hydrochloric acid, in order to 

 combine with the ammonia ; " and further on, he observes, " It 

 is the difference of solubility of subcarbonate of hme and hydro- 

 chlorate of ammonia, which occasions the double exchange of 

 the bases and acids ; and consequently it is on account of that 

 difference of solubility that water is decomposed." 



Now with much deference I think this reasoning can scarcely 

 be admitted. Surely the insolubility of carbonate of hme cannot 

 act until the carbonate exists, and the decomposition, for which 

 this insolubility is adduced to account, must occur before it. If, 

 however, the kind of reasoning employed by M. Gay-Lussac is 

 admitted, then we may certainly account for the decomposition 

 of chloride of mercury, by supposing that it results from the 

 ^affinity of uncreated muriatic acid for ammonia. 

 ' ^ After having considered the subject (I confess with much 

 less attention than the intricacy of it requires), I incline to 

 the opinion that all soluble chlorides are converted into muriates 

 by solution in water. I think it will appear, from what I have 

 stated, that fewer decompositions must be supposed to occur on 

 this supposition than the other ; and it is to be recollected, in 

 support of this opinion, that no objection, as far as I know, has 

 been made against the idea of the decomposition of water as it 

 respects sulphuret of potash, or rather potassium. 



Admitting (what, however, I am by no means disposed to 

 assert) that the opinion which I have adopted to is most proba- 

 ble,^ the question still remains to be decided, under what point 

 of view shall we regard those chlorides, or muriates, which 



