84 TlMEHRl. 
Trinidad, and every one of them contained prussic acid, 
nine out the number (or 60 per cent), yielding sufficient 
from one pound of the root or half a pint of the juice to 
kill an adult. 
The following summary shows the average as well as 
the highest and lowest quantities of prussic acid, that 
were met with in fifteen samples of sweet and ten sam- 
ples of bitter cassava : — 
Sweet Cassava (is Samples.) Bitter Cassava (io Samples) 
Per cent, of Gh'ains of Per cent, of Grains of 
P? , ussic Acid. Prussic Acid per lb. Prussic Acid. Prussic Acid per lb. 
Average -0168 ... 1-175 ... -0275 ... 1-927 
Highest -0238 ... 1-666 ... -0442 ... 3-094 
Lowest -0113 ... 0-791 ... -0132 ... 0-924 
Full particulars as to the mode in which the prussic 
acid was estimated have been already given. It will be 
seen that no great difference exists in the amount of prus- 
sic acid in the two varieties : one pound of either root 
would, on the average, furnish a fatal dose of the poison.* 
It appears that the older cassava grows, the more 
poisonous it becomes. It is known to local provision 
farmers that the variety of sweet cassava called " Buck- 
stick" is harmless when young but poisonous when old. 
The writer examined one very old specimen of sweet 
cassava. Some of the tubers were of immense size, 
and almost globular in shape. They yielded '0352 per 
cent, of prussic acid, equal to no less than 2*464 grains 
to the pound. From an amount of juice equivalent to 
three pounds of the tubers there were obtained 6^ fluid 
drachms of diluted prussic acid of British Pharmacopoeia 
* Dr. Taylor fixes the poisonous dose of prussic acid at one grain, but 
at the same time reports the case of a healthy woman who died in 
twerjty minutes from a dose containing nine-tenths of a grain. — On 
Poisons, 3rd edit. p. 594. 
