THr. SWEET POTATO. 45 



Tscliircli and Oesterle (Anat. Atlas tier Pbarmac. 

 mid Nalirungsm., p. 229) treat sweet potato starch 

 under "Brazilian arrowroot," and state that it is 

 manufactured everywhere in the tropics, as, for 

 example, in India. 



We have the statements, then, that sweet potato 

 starch is actually used for technical purposes now, 

 and that it is manufactured on a more or less 

 extended scale by crude methods. As far as known 

 to the writer, no thorough experiments have ever 

 been made to manufacture sweet potato starch by 

 modern processes on a scale sufficiently extensive to 

 warrant accurate conclusions. This question the 

 writer intends to take up in the future. 



C. The Sweet Potato as a Source of Sugar. 



It has often been suggested that the sweet potato 

 would be a valuable source of cane sugar, and the 

 sugar beet, in which the sugar contents have been 

 raised greatly by proper selection, is cited as an 

 illustration of what can be done. It is true that 

 some varieties of sweet potatoes, especially after 

 storing, are much higher in cane sugar percentage 

 than the sugar beet was at the beginning. The 

 Texas station Bulletin 36, for example, reports a 

 percentage of cane sugar as high as 12.46 in the 

 "Early Bunch "Yam." The great difficulty is that 

 the 12.46 per cent, of cane sugar are accompanied by 

 7.25 per cent, of glucose, which is noncrystallizable, 

 and which, besides, prevents the larger part of the 

 cane sugar from crystallizing. It may be well to 

 remember here that sorghum cane, which has a 

 more favorable cane sugar percentage (up to 14 

 per cent, of cane sugar with 3-4 per cent, of glucose) 



