Mr. E. A. Parnell on Snlphocyanogen. 253 



observe an error in the conclusion at which he had arrived, 

 it must not be forgotten that it is by his refined and beauti- 

 fully simple method of analysis that I have been able to attain 

 my results. 



For convenience, I shall continue in the remainder of this 

 paper to speak of the substance derived from the sulpho- 

 cyanides as sulphocyanogen. 



2. Action of Alkalies on Sulphocyanogen. 



We are indebted to Wcehler and Liebig for all that is as 

 yet known respecting the action of alkalies on this substance ; 

 but this subject was not studied so completely by them as 

 it appears to deserve, nor so satisfactorily as other points 

 connected with the sulphocyanides in their remarkable re- 

 searches. 



It appears from their experiments, that when sulphocyano- 

 gen is digested in solution of potash, a small portion is dis- 

 solved, and the remainder becomes redder, partly soluble in 

 water, and partly in alcohol. After alcohol and water had 

 been successively applied to this altered sulphocyanogen until 

 nothing more was dissolved, a clear yellow substance re- 

 mained, which Liebig considered as a higher degree of sul- 

 phuration of cyanogen. But his analyses of this substance 

 do not sufficiently accord with any theoretical numbers to 

 decide its constitution. 



My own experiments certainly confirm the above as far as 

 they go, but it would appear that heat had not been applied 

 to the mixture of sulphocyanogen and alkali, but that it had, 

 on the contrary, been kept at common temperatures ; for if 

 sufficient potash had been present and a gentle heat applied, 

 the whole of the sulphocyanogen would have been dissolved, 

 and converted into other substances. 



When three parts of sulphocyanogen are digested with 

 about four parts of potash and twenty or twenty-five of water, a 

 portion is at once dissolved, the remainder, on the appli- 

 cation of a gentle heat, forming a reddish yellow transparent 

 solution, from which acids throw down a yellow precipitate, 

 which is a mixture of two substances, one of a light lemon 

 colour, the other brown, or almost black. The appearance of 

 the changes which are here undergone, varies considerably 

 with the manner of performing the operation. If, for in- 

 stance, the sulphocyanogen be in excess, it is either not en- 

 tirely dissolved, or if it is, the precipitate produced by acids 

 contains unaltered sulphocyanogen : on the contrary, if the 

 alkali be in excess, the decomposition is more complete, the 

 precipitate has a much lighter colour, and does not appear 



