86 TlMEHRI. 
iii the distillate. But one hundred grammes of the same 
sample of cassava grated raw, mixed with water and 
distilled in the same way gave "0444 gramme of prussic 
acid, equal to 3*094 grains in the pound. 
Thorough cooking is necessary however to altogether 
prevent the development of prussic acid in cassava, as 
the following experiments show. 
A large sample of sweet cassava was obtained, and by 
three separate determinations it was found to yield when 
grated raw an average quantity of 1.551 grains of prussic 
acid to the pound. Less than three-quarters of a pound 
would therefore furnish a poisonous dose of the acid. 
Five hundred grammes (rather more than one pound) 
consisting of three whole roots of the sample were plunged 
into boiling water, and kept boiling moderately for one 
hour. The roots were then taken out, allowed to cool, 
and after being mashed with water, the prussic acid in 
them was estimated and found to be .0294 grain in the 
pound. It would therefore require 34 pounds of the 
boiled root to yield one grain or a poisonous dose of 
prussic acid. 
Five hundred grammes of the same sample were then 
boiled for half an hour, cooled, mashed with water and 
the prussic acid determined as before. They yielded 
.0325 grain of prussic acid per pound or one grain from 
30.7 pounds of the boiled root. 
Five hundred grammes were again boiled for 15-20 
minutes and on cooling yielded .084 grain of prussic acid 
per pound, or one grain from 11.9 pounds of the boiled 
root. 
