129 
mth Cyanide of Mercury, 
23*5 grains corresponding to 58*75 per cent, containing 50*13 
mercury, equivalent to 63*05 of cyanide. 
The liquor from which the mercury had been thus sepa- 
rated, was evaporated carefully to dryness, and the salt ob- 
tained was deprived of all water of crystallization by exposure 
to a temperature of 300°, until it ceased to lose weight. It 
then weighed 3T32. It was pure dry ferrocyanide of potas- 
sium. 
A quantity of the new salt equal to 50*4? grains was ig- 
nited and icinerated; the residue then treated by muriatic 
acid, and the iron thrown down by ammonia added in excess. 
The oxide of iron weighed contained 2*23 of metallic iron, 
corresponding to 4?*47 per cent. 
The liquor after the separation of the iron was evaporated 
to dryness, and ignited ; there remained chloride of potassium, 
equal to 12*3, containing 6*51 potassium or 12*91 per cent. 
This new salt, therefore, contained 
Mercury 50*13 
Iron 4? *4? 7 
Potassium 12*91 
Water 5*78 
Loss and cyanogen 26*71 
100*00 
The relation is exactly such that the mercury employs 
half of the cyanogen to form cyanide of mercury, and the re- 
maining half forms with the potassium and the iron common 
ferrocyanide of potassium : the result as calculated should be 
3 
atoms mercury 
50*26 
2 
potassium .... 
13*11 
1 
■ iron , ,, 
28*0 
4*62 
6 
cyanogen....... 
26*07 
4* 
• water 
5*94 
605*4 
100*00 
1 he existence of this salt is of considerable practical im- 
portance, as it shows the necessity of avoiding any excess of 
ferrocyanide of potassium in preparing cyanide of mercury ; 
an error into which, from motives of oeconomy, the manu- 
facturing operator would be peculiarly liable to fall. 
23 , Gloucester Street, Dublin, Dec. 23 , 1839. 
Phil, May, S. 3,, Vol, 16. No. 101. Feb, 184?0. 
K 
