106 REPORT — 1859. 



of arsenite of silver in nitric acid, and adding this very gradually to a boiling 

 concentrated solution of soda, an extremely black powder was produced. 

 This on being treated with dilute chlorhydric acid becomes grey; and on 

 boiling the washed product with dilute nitric acid, silver is dissolved, and 

 there is left a substance, which, if Wohler be right in calling the black pow- 

 der suboxide of silver, we should expect to contain subchloride of silver. 

 The colour of this substance is a rich chocolate or maroon, more or less dark, 

 according to the nature of the process : it never reached the deep slate-violet 

 of the chloride of silver exposed to sunlight. On analysis it was found to 

 contain as large an amount as 24 per cent, of chlorine ; 



The pure chloride Ag CI contains 24"74 of chlorine; 

 The subchloride Ag 2 CI requires 14 - 08 of chlorine. 



Other products of less-deep hue than the one first examined gave the numbers 

 24'3 and 24*2 per cent, of chlorine. Assuming that the chocolate hue was 

 imparted to the substance by a subchloride (and no other view seems equally 

 probable), we are constrained to recognize in this subchloride, only present 

 to the amount at the furthest of 5 per cent., a surprising colorific energy. 



From the experiments previously cited, we are disposed to think that our 

 failure in this attempt to produce the pure subchloride of silver arose from 

 the fact of the action of chlorhydric acid upon the suboxide of silver not being 

 so simple as a complete conversion into subchloride would indicate; and we 

 are the more induced to draw this conclusion from the analogy of the sub- 

 oxide of mercury. Thus, if from a solution of the suboxide of mercury 

 that oxide be precipitated, the action of chlorhydric acid on the precipitate is 

 not to form the subchloride, but a grey mixture of chloride and metallic 

 mercury. The same may perhaps apply to suboxide of silver ; and, if so, it 

 would be decomposed by chlorhydric acid, either partially or entirely, and 

 would form chloride of silver and metallic silver. 



One experiment we tried, in the hope of producing the subchloride of 

 silver by a direct reaction. Chloride of silver is soluble in concentrated and 

 highly alkaline arsenite of soda; and this solution, in the presence of excess 

 of soda, was gently warmed. A brilliant inirror-like deposit, not of sub- 

 chloride, but of metallic silver, was the result. 



But with however little success the efforts to produce a pure subchloride 

 of silver have as yet been crowned, the experiments we have detailed enabled 

 us to institute a few comparative reactions whereby the result of treating a 

 true subchloride (however diluted, so to say, with protochloride) with the 

 ordinary reagents employed by the photographist may be achieved. The 

 results yielded by these reagents were the following : — 



Nitric acid, of sufficient strength to dissolve silver by heat, does not alter 

 this dark compound. 



Chlorhydric acid does not, when dilute, produce any apparent change 

 in it. 



Ammonia breaks it up entirely, dissolving all as chloride, except a minute 

 amount of metallic silver, which remains. 



Hyposulphite of Soda dissolves all except a trace of metallic silver like 

 that left by the ammonia. 



It will hardly be worth while to go through the reactions exhibited by 



capable of yielding a solution of silver when treated by nitric acid. So utterly unstable are 

 these subcompounds of that metal ! 



Indeed it would seem that to secure to them any permanence, they must be formed in 

 .combination. 



