FRANCIS — ON CASSAVA. 
117 
These results are recorded in a paper — “ On Prussic Acid 
from Cassava” — published in the London Analyst for April, 
1877, which included the following table, showing the amount 
of prussic acid yielded by a number of different samples of 
bitter and sweet cassava ; the quantities being given in per- 
centages and also as grains of prussic acid from an avoirdu- 
pois pound of the fresh root. 
TABLE I. 
Quantity of Prussic Acid yielded by Cassava Roots. 
Sweet. 
Bitter. 
No. of 
Per cent 
Grains of 
No. of 
Per cent. 
Grains of 
Sample. 
of H C N. 
H C N per lb. 
Sample. 
of H C N 
H C N per lb. 
i. 
•0158 
1-106 
i. 
•0377 
2-639 
ii. 
•0121 
0-847 
ii. 
•0237 
1-659 
iii. 
•0125 
0-875 
iii. 
•0442 
3-094 
iv. 
•0138 
0-931 
iv. 
•0440 
3080 
v. 
•0113 
0-791 
V. 
•0132 
0-924 
vi. 
•0194 
1-358 
vi. 
•0209 
1-463 
vii. 
•0226 
1 -582 
vii. 
•0348 
2-436 
viii. 
•0199 
1-393 
viii. 
•0221 
1-547 
ix. 
•0208 
1-456 
ix. 
•0133 
0-931 
X. 
•0238 
1*666 
x. 
•0215 
1-505 
xi. 
•0202 
1-414 
xii. 
•0134 
0-938 
xiii. 
•0202 
1-414 
xiv. 
•0149 
1-043 
XV. 
•0117 
0-819 
Mean 
•0168 
1-175 
Mean 
•0275 
1-927 
Highest 
•0238 
1-666 
Highest 
•0442 
3-094 
Lowest 
•0113 
0-791 
Lowest 
•0132 
0-924 
The samples indicated in the table were obtained from as 
many sources as possible ; some from stalls in the public 
markets, others direct from the different cultivators, pains 
being taken to avoid substitution of one kind for the other. 
To separate the prussic acid from cassava in a form 
adapted for estimation, distillation was essential, but the 
80 per cent, of starch which the roots contain had to be 
excluded from the retort. In order to accomplish this 
