210 poisons: their effects and detection. [§§ 261,262. 
particular class. A fair proportion of the deaths are also due to 
accident or unfortunate mistakes, and a still smaller number to the 
immoderate or improper use of cyanide-containing vegetable products. 
§ 261. Accidental and Criminal Poisoning by Prussic Acid. —The 
poison is almost always taken by the mouth into the stomach, but 
occasionally in other ways—such, for example, as in the case of the 
illustrious chemist, Scheele, who died from inhalation of the vapour of 
the acid which he himself discovered, owing to the breaking of a flask. 
There is also the case related by Tardieu, in which cyanide of potassium 
was introduced under the nails ; and that mentioned by Carriere, 1 in 
which a woman gave herself, with suicidal intent, an enema containing 
cyanide of potassium. It has been shown by experiments, in which 
every care was taken to render it impossible for the fumes to be inhaled, 
that hydrocyanic acid applied to the eye of warm-blooded animals may 
destroy life in a few minutes. 2 
With regard to errors in dispensing, the most tragic case on record 
is that related by Arnold : 3 —A pharmaceutist had put in a mixture 
for a child potassic cyanide instead of potassic chlorate, and the child 
died after the first dose : the chemist, however, convinced that he had 
made no mistake, to show the harmlessness of the preparation, drank 
some of it, and there and then died ; while Dr Arnold himself, in¬ 
cautiously tasting the draught, fell insensible, and was unconscious for 
six hours. 
§ 262. Fatal Dose. —Notwithstanding the great number of persons 
who in every civilised country fall victims to the cyanides, it is yet 
somewhat doubtful what is the minimum dose likely to kill an adult 
healthy man. The explanation of this uncertainty is to be sought 
mainly in the varying strength of commercial prussic acid, which varies 
from 1-5 (Schraeder’s) to 50 per cent. (Robiquet’s), and also in the 
varying condition of the person taking the poison, more especially 
whether the stomach be full or empty. In by far the greater number, 
the dose taken has been much beyond that necessary to produce death, 
but this observation is true of most poisonings. 
The dictum of Taylor, that a quantity of commercial prussic acid 
equivalent to 1 English grain (65 mgrm.) of the anhydrous acid would, 
under ordinary circumstances, be sufficient to destroy adult life, has 
been generally accepted by all toxicologists. The minimum lethal dose 
of potassic cyanide is similarly put at 2-41 grains (-157 grm.). As to 
bitter almonds, if it be considered that as a mean they contain 2-5 per 
cent, of amygdalin, then it would take 45 grms., or about 80 almonds, 
1 “ Empoisonnement par le cyanure de potassium, — guerison,” Bullet, genera} 
de Therap., 1869, No. 30. 
2 N. Grehaut, Compt. rend. Soc. Biol. (9), xi. 64, 65. 
3 A. B. Arnold, “ Case of Poisoning by the Cyanide of Potassium,” Amer. Journ. 
of Med. Science, 1869. 
