154 



Drs. Dunstan, Henry, and Auld. [Apr. H> 



The first observation as to the volatile nature of the poison contained in the 

 roots seems to have been made by Fermin,* who obtained from 50 lbs. of 

 manioc juice 3 ounces of an intensely poisonous distillate, 35 drops of which 

 were sufficient to poison in a few seconds a condemned slave to whom they 

 were administered. In 1828, according to Henry and Boutron-Charlard,f 

 Soubeiran and Pelletier endeavoured to isolate the toxic principle of cassava, 

 but were unsuccessful. In 1833 Henry conducted a similar investigation, 

 but owing to lack of material was unable to obtain any definite results. The 

 same author, in association with Boutron-Charlard, took up the matter again 

 in 1836,$ and succeeded in identifying the poisonous volatile constituent of 

 cassava with hydrocyanic acid. 



It is worth noting in this connection that although Scheele had discovered 

 hydrocyanic acid in 1780, he was apparently unaware that it was poisonous. 

 The toxicity of the acid was first established by Henry and Boutron-Charlard 

 in 1833. These authors made a complete analysis of cassava, and found that 

 the roots contained starch, free hydrocyanic acid, sugar, an organic magnesium 

 salt, a bitter principle, a fat, a nitrogenous substance, calcium phosphate, 

 and woody fibre. They also carried out a number of physiological experi- 

 ments with fowls, and found that the distillate prepared from cassava 

 invariably produced fatal results when administered. 



The first trustworthy estimations of the amounts of hydrocyanic acid 

 obtainable from cassava were made by Francis,§ who established the 

 important fact that, as regards the cassava roots grown in the West Indies, 

 both the " sweet " and " bitter " varieties yield about the same quantities of 

 hydrocyanic acid. 



Francis' observations as to the occurrence of hydrocyanic acid in the 

 " sweet " as well as in the " bitter " cassava grown in the West Indies were 

 confirmed by CarmodyJ who concluded that the principal difference between 

 the two plants is that in the " bitter " cassava the acid is uniformly 

 distributed throughout the root, whereas in the " sweet " cassava it is located 

 principally in the rind of the root. Carmody also observed that in sweet 

 cassava the acid occurs partly free and partly combined. 



In 1886 PeckoltlT examined a number of the principal varieties of cassava 

 grown in Brazil, and showed that most of these, both the " sweet " and 



* ' M6m. Acad. Sci. Berlin,' 1764. 



t 'Mem. Acad. Eoyale de Medecine,' Paris, 1836, vol. 5, p. 212. 

 | Loc. cit. 



§ ' Analyst,' 1870, vol. 2, p. 4. 

 || ' Lancet,' 1900, 



IT ' Pharm. Eund.,' 1886, vol. 4, p. 227. 



