258 Mr. E. A. Parnell on Snlphocyanogen. 



with decomposition in nitric acid, and by boiling in hydro- 

 chloric acid, sulphuretted hydrogen being evolved in the latter 

 case. The affinity of silver for the radical of this acid ap- 

 pears stronger than for chlorine ; for if this acid and hydro- 

 chloric acid be present in the same solution, and nitrate of 

 silver added, the thiocyanide of silver is first precipitated. It 

 is insoluble in ammonia. 



19*60 grains were treated with hot nitric acid, which dis- 

 solved it ; the silver was precipitated by hydrochloric acid, 

 and nitrate of barytes added to the filtered solution to obtain 

 the sulphuric acid. 



The chloride of silver amounted to 18*25 grains, or 13*747 

 of silver, equal to 70' 14 per cent. The sulphate of baryta 

 amounted to 21'24 grains, equal to 2*94 of sulphur: sulphur 

 not converted into sulphuric acid, separated on a weighed filter, 

 amounted to '20 grain, = 3*14 or ] 6*01 per cent, of sulphur. 



The proportion of silver here is just twice as great as the 

 proportion of lead in the salt of that metal. In fact, it ap- 

 pears to be a double thiocyanide and oxide of silver, or a sub- 

 salt : thus They 4 Aq + 4 Aq O, which by theory should 

 contain Found. 



Sulphur 15*80 16'01 



Silver 70'78 70-14 



As the neutral thiocyanides are yellow and the subsalts 

 black, so we have reason to believe that the yellow silver 

 compound is the neutral thiocyanide; but this cannot be de- 

 cided by analysis, on account of the rapid change which it 

 undergoes. 



Mercury. Nitrate of protoxide and chloride of mercury are 

 precipitated by the aqueous solution of this acid. The pre- 

 cipitate is at first white, but by heating it becomes yellow. In 

 its properties it resembles the copper and lead salts; like them 

 it is converted into a subsalt by alkalies, and it gives similar 

 products on heating. Nitric acid instantly acts on it; a white 

 compound is produced which undergoes no further change 

 by nitric acid alone, but on the addition of hydrochloric acid 

 it is immediately dissolved. 



Nitrate of suboxide of mercury gives the black subthio- 

 cyanide. Chloride of platinum and bichloride of tin are pre- 

 cipitated yellow by solutions of the acid, but I have not ex- 

 amined these precipitates. 



Such is the incomplete investigation I have had it in my 

 power to make of these compounds. As the sulphocyanogen 

 derived from the sulphocyanides does not appear to be what 

 it was considered, but a highly complicated substance, the in- 



