462 Scientific Notices — Chemistry, [Dec. 



It was also shown in the memoir above alluded to that cyanic 

 acid is composed of an atom of cyanogen, and one of oxygen, 

 and it appeared to us that in the acid obtained with the cyanate 

 of silver and sulphuretted hydrogen, that oxygen was exactly 

 replaced by sulphur, and that we had obtained a compound of 

 sulphur and cyanogen. Such are the results which have been 

 stated in the memoir ; sometime since I undertook some expe- 

 riments to determine with more precision the nature of the acid 

 obtained by decomposing cyanate of silver with sulphuretted 

 hydrogen. The results of these observations are slightly dif- 

 ferent from those which we had previously obtained, but we 

 have not paid minute attention to these several acids. 



If sulphuretted hydrogen gas be passed through water, hold- 

 ing cyanate of silver in suspension, and if the hquor be strongly 

 agitated before the cyanate is totally decomposed, an extremely 

 penetrating smell is perceived, and ammonia, when exposed to 

 the mixture, produces a white cloud. As soon as the salt is 

 entirely decomposed, which happens when the fluid becomes 

 clear, this smell is no longer perceptible. The liquid separated 

 by the filter from the sulphuret of silver has an acrid taste, and 

 reddens turnsol ; when mixed with lime ammonia is expelled, it 

 precipitates muriate of barytes after being heated with nitric 

 acid, gives a bulky precipitate with nitrate of silver, and 

 changes the persalts of iron to a deep red colour ; it appears 

 from this that the cyanic acid, decomposed by the sulphuretted, 

 is converted into a cyanite (?) of ammonia, and a peculiar acid 

 containing sulphur, but different from the sulpho-cyanic acid. 

 The fluid, when left for some time exposed to the air, deposits 

 a yellow powder, and then the smell of hydrocyanic acid is 

 perceived ; the solution by spontaneous evaporation yields a 

 deliquescent salt, which, with acid, gives the penetrating smell 

 of sulpho-cyanic acid. 



As it is extremely probable that the formation of ammonia 

 had been determined by the affinity of the acid, I made another 

 experiment to decompose the cyanate of silver with sulphuret 

 of barium, obtained by decomposing sulphate of barytes with 

 lamp black ; the sulphuret of barium was gradually added 

 to the cyanate suspended in boiling water, as long as sulphuret 

 of silver was formed ; the filtered liquor was very alkaline, but 

 it gave no sulphuretted hydrogen on the addition of an acid ; 

 nitrate of silver gave a yellow precipitate, which became black 

 on drying. A current of carbonic acid gas passed through the 

 solution, produced only a small quantity of carbonate, and by 

 evaporation a yellow salt was procured, which heated to 100° 

 cent, burnt without giving light, till it lost all its moisture, and 

 it became grey : it was then treated with water, which dissolved 

 a sulpho-cyanuret of barium, and carbonate of barytes re- 

 mained : the acids separate sulpho-cyanic and carbonic acids, 

 and lime evolves ammonia. Wiheu heated in glass tubes after 



