POTATO-STARCH. 323 



been boiled or otherwise cooked. The heat of the stomach is 

 not sufficient to burst all the grains of the amylaceous mass 

 which is subjected to the rapid action of this organ. The 

 stomach of graminivorous animals and birds seems to possess, 

 in this respect, a particular power, for they use amylaceous 

 substances in a raw state. Nevertheless, recent experiments 

 prove the advantage that results from boiling the potatoes, and 

 partially fermenting the farina, given to them for food. At all 

 events, it is certain that bruised grain is much more nutritive 

 for them than that which is entire ; for a large proportion of 

 the latter passes through the intestines perfectly unaffected as 

 when it was swallowed. Branconnot found unbroken starch 

 grains in the excrement of a slug, and also in the excrements 

 of warm-blooded animals fed on raw potatoes. 



In short, the exterior laminae of the starch granules are 

 thicker and more cohesive than the inner ones, and therefore 

 present greater resistance to the digestive power of the 

 stomach. 



Potato-Starch. Potatoes contain about 20 per cent of amy- 

 laceous matter. The cellular tissue of the tuber does not 

 exceed 2 per cent ; of the remainder, 76 per cent consists of 

 water, with very small quantities of citric acid, sugar, salts, and 

 azotised matters. The potatoes are reduced to a pulp, which 

 is washed on a sieve, so long as the water runs off turbid. 

 The milky liquid is received in vats, where the amylaceous 

 matter is allowed to subside. 



It is imported from France and from Guernsey, and is also 

 manufactured in this country. It bears the name in the 

 market of potato-flour, and is also called English arrowroot. 

 Its grains are less than those of tous-ks-mois. In France it 

 is made to resemble sago, and is sold as potato-sago. It is 

 often substituted in commerce for arrowroot. It is made into 

 potato-sugar, which is used to adulterate brown sugar. In 



