Uses of the Potaioe. 37 
period when, the potatoes begin to grow, the farina being de- 
stroyed by germination. Red potatoes produce a smaller 
quantity of farina. Those which are blue on the outside give 
little, but it is of good quality; the white, which is often ting- 
ed with red in the interior, is the least proper for this extrac- 
tion. The best of all are those which have a yellow tint, as 
the farina is of very good quality and abundant. 
The meal of potatoes may be preserved for years, closely 
packed in barrels, or unground in the form of slices, these 
slices having been previously dried by steam. Some German 
philosophers have proposed to freeze the potatoes, by which the 
feculent matter is separated from the starch, and the latter 
being then dried and compressed, may be preserved for any 
length of time, or exported with safety any distance. 
The manufacture of tapioca from potatoes is thus given in the 
Quarterly Journal of Agriculture. The potatoes selected are 
thoroughly washed, afterwards they are grated in a machine 
constructed for the purpose. The parts thus reduced or grat- 
ed fall into a vessel placed underneath. From this vessel 
they are removed, and strained into a tub. On the juice 
being well expressed for the first time, the fibrous matter is 
set apart, and cold clean water is thrown over them. The 
fibres are again put through the same strainer, till the whole 
of the substance is collected, when they are finally cast aside. 
On this being done the contents of the tub, now in a state of 
mucilage or starch, are allowed to settle. A reasonable in- 
terval being suffered to elapse, the old water is poured gently 
off, and fresh water supplied. After this process of washing 
the bleached matter is passed through a smaller strainer. 
The offals are separated; the starch now becomes much 
whiter; but still fresh water is abundantly dashed over it. 
When by frequent ablution the surface of this mass is ren- 
dered quite smooth and clear, it is filtrated a third and list 
time. 
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