326 
ON AN EXPLOSIVE COMPOUND, ETC 
ART. LVIIL— ON AN EXPLOSIVE COMPOUND FORMED DU- 
RING THE DISTILLATION OF HYDROCYANIC ACID. 
By Mr. Alsop. 
The late catastrophe at^Apothecaries' Hall, on the prepa- 
ration of fulminating mercury, has recalled to my recollec- 
tion a circumstance which took place several years since 
which may probably be interesting to the members of the 
Pharmaceutical Society. 
At the time adverted to, I was residing at the house of 
John Bell and Co. and we were accustomed to prepare hy- 
drocyanic acid, by distilling the bicyanide of mercury with 
hydrochloric acid ; on one occasion the process was stopped 
before the whole of the prussic acid had been evolved from 
the materials in the retort, which were therefore reserved to 
be added to a future distillation. This liquid, retaining 
strongly the hydrocyanic odour, was transferred to a stopper- 
ed phial and kept in a dark closet for two or three months. 
It was subsequently submitted to distillation, together with 
fresh materials, in a retort capable of holding about four pints, 
and which was more than half full. The heat of a lamp had 
not long been applied to it, when an opalescent appearance 
was manifested, and a gradual formation of exceedingly mi- 
nute and pearly crystals was observed to pervade the liquid. 
This was doubtless no other than fulminating mercury. At 
first it was supposed to be protochloride of mercury, arising 
from the decomposition of a protocyanide which appears some- 
times to be formed by acting on Prussian blue, and therefore 
did not attract much attention, notwithstanding its suspicious 
appearance. This deposit continued to increase ; it was left 
for a few minutes, and happily no one was present, when the 
laboratory was shaken by a most alarming explosion. The 
contents of the retort were discharged on the ceiling, show- 
ing that the explosion had taken place from the bottom, to 
