Experiments on Manioc. 
135 
and reduced lo a pulp with a coarse rasp or grate, and this 
pulp subjected to pressure in bags of different kinds, but that 
generally used is formed of the bark of a tree, and the pres- 
sure made by suspending weights to its bottom; the liquid 
which is forced out is received in proper vessels. 
The cassava is prepared by taking the pulp thus freed from 
the juice, and spreading it about two inches thick on iron 
plates, over a fire, after which the cakes thus formed are 
dried in the sun. 
The root of the manioc furnishes a great quantity of fecula, 
which is prepared in the usual way, and sold under the names 
starch, cipipa, or moussache. Washerwomen make use of 
it, but prefer arrow root, which they erroneously term sago. 
It is important in the practice of medicine to ascertain the 
origin of the feculas sold in the shops, for serious conse- 
quences have resulted from the administration of that of the 
manioc. 
Those parts of the pulp which remain on the sieve, are 
dried, slightly roasted and contused, so as to form a very 
coarse powder, termed flour of couscous or tapioca, w r hen boiled 
with milk it forms an excellent article of food. 
The root of the bitter manioc, as has already been stated^ 
is very poisonous, and it is evident from the above, that its 
poisonous principle resides in the juice ; this principle 
appears to be very volatile, and its penetrating odour 
resembles that of hydrocyanic acid. Nevertheless, al- 
though the juice of the bitter manioc is extremely dan- 
gerous the negroes often apply thick layers of the recent pulp 
on large ulcers, without experiencing any other effects than 
a marked melioration of the disease. It is probable then, that 
if hydrocyanic acid forms part of the poisonous principle, in 
such proportions as are indicated by the smell of the juice 
and the volatility of the poison, this pulp could not be applied 
with impunity on surfaces of so great an extent,, even making 
all due allowances for the diminished vitality of the parts, for 
it is only to old fungous and callous ulcers that it is applied. 
Dr. Sureau has also transmitted to me, a case exemplifying 
the poisonous action of this juice, which possesses no slight 
interest. 
