Uses of the Potatoe. 37 



period when the potatoes begin to grow, the farina being de- 

 stroyed by germination. lied 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. 



Tl*e 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 last 

 time. 



4 



