Hydrocyanic Acid fyc. 
165 
that the frightful difference of strength had induced me to 
make the results known, with a view of calling the attention 
of the medical profession to the evil. Thus, samples from 
Allen, Hanbury and Co., yielded 5-8 per cent.; from Apothe- 
caries' Hall, at different times, from 2-1 to 2-6 per cent.; and 
from several sources I found acid containing only 1.4 per 
cent. These samples I procured from the several shops per- 
sonally, and asked for Scheele's strength. , They were assayed 
within 24 hours after they were in my possession, both by the 
nitrate of silver and the oxide of mercury method, and the 
results in no cases varied more than one-tenth of a grain 
from each other. Now, it is true we have no fixed standard, 
and therefore it is impossible to say whether Allen and Co.'s 
is too strong or the others too weak; but this much is certain, 
that if a medical man were pushing the exhibition of hydro- 
cyanic acid gradually to a maximum dose, the prescriptions 
being carried to a shop where the acid had only one-fourth 
per cent, and then by some accident or other cause taken to 
where Allen's acid was used, a sudden, and I fear a fatal in** 
crease would be the result, for more than a triple quan- 
tity would be taken. For the possibility of a fatal acci- 
dent, I need only refer to the case of seven individuals near 
Paris being killed by a slightly increased dose, recorded in 
all the medical periodicals a few years since. 
(9.) On the same evening I called the attention of the mem- 
bers of the Medico -Botanical Society to the method for pro- 
curing medical hydrocyanic acid recommended by Dr. Tho- 
mas Clarke, by cyanide of potassium and tartaric acid ; a 
method which can now be employed by any one, since Mr. 
Laming has brought into the market a very pure salt. From 
very numerous trials, I find that the procuring of this salt, 
the cyanide of potassium perfectly pure, must be expensive ; 
and I have never been able to procure it strictly in this state 
without using alcohol to crystallize it from : and many che- 
mists, I find, (see Mr. Barry's paper above alluded to,) object 
to it, from its being so excessively deliquescent, and hence 
rather unmanageable, and also to the liability of this highly 
poisonous salt being mistaken for other white salts on? their 
