SWEET-POTATO 429 



On the table, among the dishes rich in protein are peas, 

 beans, milk, eggs, and lean meat. In the diet of animals, 

 suitable foods for supplementing sweet-potatoes are pea- 

 nuts, the seeds of cowpeas, soy beans, the hay of any of the 

 legumes, and cotton-seed meal. The figures show that 

 the sweet-potato root contains about one and one half 

 times as much nutritive matter as an equal weight of Irish 

 potatoes. 



Moreover, the protein, or nitrogenous portion in Irish pota- 

 toes, is chiefly in the less valuable form, amides ; while it has 

 been found that amides are not present in the mature sweet- 

 potato, all the protein here being in a more valuable form. 



Compared with shelled corn, 300 pounds of sweet-potato 

 roots afford slightly m.ore total dry matter and carbonaceous 

 material (as starch and sugar) and a httle less protein ; the 

 theoretical nutritive value of sweet-potatoes is approximately 

 one third that of an equal weight of shelled corn. 



In order to make advantageous use of the sweet-potato as a 

 hog food, it is necessary to use only the unmarketable roots ; 

 or else to require the hogs to harvest the crop, thus avoiding the 

 principal item of expense for labor. 



398. Starch and alcohol. — It seems probable that the 

 sweet-potato will become an important crop for the manu- 

 facture of starch, an excellent quality of which has been 

 made from this crop. Sweet-potatoes usually contain 

 15 to 20 per cent of starch. This is a higher percentage 

 than in the Irish potato, which is now a standard source 

 of starch. 



Recent laws permitting, under certain restrictions, the 

 manufacture of denatured alcohol for use as fuel and in the 

 arts, make it probable that the sweet-potato will be ad- 

 vantageously manufactured into this product. A bushel 



