116 PROCEEDINGS OF THE SCIENTIFIC ASSOCIATION. 
juice of bitter cassava, compared the action of the poison to 
that of prussic acid ; and Dr. Fermin, in a memoir commu- 
nicated to the Academy of Berlin, concerning experiments 
made at Cayenne upon the juice of the manioc, showed that 
the poison was volatile and could be isolated by distillation. 
He gives particulars of an experiment in which fifty pounds 
of the fre ;h juice yielded by distillation three ounces of a 
poisonous liquid of most offensive odour, thirty-five drops 
of which being administered to a criminal slave, caused his 
death in six minutes, amid horrible convulsions. 
Subsequently, MM. Henry and Boutron-Charland, by an 
examination of juice imported into France, identified in it the 
presence of prussic acid, and also found the effects produced 
on animals indicated that poison (Mem. de VAcad. de 
Med ., v., 212). In 1838, Dr. Christison confirmed this dis- 
covery in some well-preserved juice from Demerara (On 
Poisons , 4th edit., p. 591). 
Notwithstanding this early identification of the poison, no 
attempts appear to have been made to determine the quantity 
of the poisonous acid yielded by the plant. The present 
writer, therefore, undertook an experimental inquiry into the 
subject, not only because it offered a certain intrinsic 
interest, but also because occasions may arise when a know- 
ledge of the quantity of cassava likely to cause death might 
be important from a medico-legal aspect. 
The investigation ultimately extended to both kinds of the 
plant, and resulted in the discovery of the singular fact that 
the so-called sweet or harmless cassava not only yielded 
prussic acid, but the quantity obtained from it so nearly 
equalled that from the bitter that no line of distinction could 
be drawn between them. 
