Hydrocyanic Acid fyc. v 161 
Hence 
2 proportions of salt 212.47 X 2 
6 proportions of sulphuric acid 40 X 6 
= 424.94 
— 240.00 
•664.94. 
yield 
3 proportions of hydrocyanic acid 27.39 x 3 
3 proportions of bisulph. of potassa 127.15 X 3 
3 proportions of water 9.00 X 3 
= 82.17 
== 381.45 
= 27.00 
1 proportion of yellow salt K Cy 65.54 + 2 Fe Cy 108.78 — 174.32 
(3,) This was proved as follows : 
(a.) 212-5 grains of the crystals of ferrocyanuret of potas- 
sium were dissolved in two fluid oz. of water, to which were 
added 600 grains of dilute sulphuric acid of specific gravity 
1*179, containing 20 per cent, of real acid, and therefore 
amounting in all to 120 grains real acid; the mixture was kept 
boiling in a vessel partially closed to prevent the free ingress 
of air, till the odour of hydrocyanic acid ceased to be given 
off; the yellow salt collected, washed, and dried at 220°, 
weighed in Experiment No. 1, 88-1 grs. ; No. 2, 88-0 grs. ; 
No. 3, 87-lgrs. The calculated number is 87-16. The salt is 
very liable to assume a delicate green tint unless the air be very 
carefully excluded from the vessel, and hence its true colour 
cannot be seen, unless the flask, previously to adding the 
acid, be filled with carbonic acid gas: the green tint always 
goes off on drying it at about 300° F. 
(b.) The colourless solution which passed the filter, leaving 
the yellow salt on it, and which contained the bisulphate of 
potassa, required, to render it neutral, of crystallized bicarbo- 
nate of potassa, (I used this as being the most definite and 
manageable salt we have,) in 
Experiment No. 1, 152.1; No. 2, 151,0; No. 3, 150.6 grs. 
The calculated quantity is l£ (K + 2 C + 1 Aq) 150.58 grs., 
showing that three proportions of sulphuric acid had taken 
up only 1^ potassa. After neutralizing the liquid with bicar* 
bonate of potassa, it was in two cases evaporated to dry- 
ness, and the neutral sulphate weighed, which confirmed in 
both cases the above results, and proved that no other salt 
was in the solution : also, in one case, the sulphuric acid was 
Vol. I. — No, 2. 21 
-664.94. 
