128 Dr. Kane 07i a new Compound of Ferrocyanide 



Although Mr. Sturgeon has gone far out of his way to twist 

 these phaenomena into an accordance with certain theoretical 

 views, and sets them up as being of an extraordinary kind, 

 they are nevertheless of a very simple character, and are 

 merely illustrative of a few well-known laws of electrical 

 action. 



[To be continued.] 



XXI. On a new Compound of Ferrocyanide of Potassium, 

 with Cyanide of Mercury. By Robert Kane, M.D., 

 M.R.I.A* 



T had frequently occurred to me to notice that, in the pro- 

 cess for obtaining cyanide of mercury by the action of 

 ferrocyanide of potassium on sulphate of mercury, it was 

 necessary to observe accurately the equivalent proportions of 

 these substances, in order to ensure success. If any ferro- 

 cyanide of potassium were present in excess, a corresponding 

 deficiency in the quantity of the cyanide of mercury always 

 occurred. I at last traced this circumstance to the fact, that 

 the ferrocyanide of potassium in excess combines with the 

 cyanide of mercury, to form a new substance so similar in ap- 

 pearance to the former of the two, as to be very easily con- 

 founded with it and thus rejected in the crystallizations. 



This new salt is most easily prepared by dissolving together 

 in a moderate quantity of water about one part of ferro- 

 cyanide of potassium in crystals with two of cyanide of mer- 

 cury. On cooling, the new salt separates in the form of 

 rhomboidal plates of a rich yellow colour, almost as deep as 

 that of ferrocyanide of potassium. When heated, these cry- 

 stals lose some water and become whitish and opake, then 

 blacken and yield cyanogen and mercury ; the usual products 

 of the decomposition of ferrocyanide of potassium remaining 

 behind. 



With a protosalt of iron, a solution of this new compound 

 yields Prussian blue, and indeed, every reagent which acts 

 on either constituent gives its characteristic reaction with this 

 new body. 



For its analysis very simple methods were sufficient. 



Forty grains dried at 300° Fahr. lost 2'31 of water or 5*78 

 per cent. 



The remaining 37*69 grains were dissolved in water, and 

 then decomposed by a stream of sulphuretted hydrogen. The 

 sulphuret of mercury was collected and dried. It weighed 



* Communicated by the Author, 



