128 Dr. Kane on a new Compound of Ferrocyanide 
Although Mr. Sturgeon has gone far out of his way to twist 
these phcenomena 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.] 
XXL On a new Compound of Ferrocyayiide of Potassium^ 
with Cyanide of Mercury. By Robert Kane, M.D., 
TT 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 
cj^anide 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. 
