On the influence of boiling on Cassava. 85 
strength ; a quantity sufficient to destroy the life of six 
adults. 
Further experiments have recently been made by the 
writer on the influence of heat on the poisonous pro- 
perties of cassava, and have proved that prussic acid 
does not exist ready formed in the tubers but is developed 
when they are sliced or grated. Moreover, moderate cook- 
ing (boiling) prevents the formation of prussic acid almost 
entirely. In both these respects cassava is like the bitter 
almond, in which no prussic acid exists until it has been 
crushed and mixed with water : then by the action of 
a peculiar ferment (synaptase), a crystalline principle 
(amygdalin) existing in the almond is decomposed into 
hydride of benzoyl, glucose and prussic acid. By first 
boiling the almond the power of the ferment is des- 
troyed and no prussic acid can be obtained. 
No doubt amygdalin exists in cassava but the attempts 
made to extract it have not yet been successful. The 
following experiments, however, show that cassava is 
affected by boiling, like the bitter almond. 
Two tubers of bitter cassava weighing together 1 1 2 
grammes (about a quarter of a pound) were thrown whole 
into a flask of boiling water connected with a Liebig's 
condenser. The contents of the flask were then slowly 
distilled into a closed receiver containing a small quantity 
of water made alkaline with pure caustic soda. After 
one hour and a half the distillation was stopped and the 
distillate tested for prussic acid, but none was present. 
On cooling, the boiled tubers were removed from the 
flask, mashed in a mortar with water, returned to the 
flask and re-distilled. Again, no prussic could be found 
