546 



Journal of Agricultural Research 



Vol. V, No. 13 



of potatoes cut lengthwise; it was therefore somewhat astonishing to 

 find considerable differences in the two halves of sweet potatoes which 

 were examined in July and August and which had been stored up to 

 that time from the previous year. On this account further examinations 

 were made of freshly dug sweet potatoes and of others of the same crop 

 which had been stored in the chambers with the experimental sweet 

 potatoes. The results of these examinations are given here. 



On September 9 three freshly dug sweet potatoes were spht dorsi- 

 ventrally as nearly as could be judged. While one half was being pre- 

 pared tor analysis the other was kept wrapped in a damp cloth. From 

 the mash of each grated half two samples were weighed out for sugar 

 determinations, two for starch, and two for moisture. From each of 

 the sugar samples and from each of the starch samples two determina- 

 tions were made. The results calculated in percentages are given in 

 Table I. The halves of the same potatoes are indicated by "a" and "b. " 

 The data afford an opportunity to estimate the error that is Hkely to 

 occur in dupHcate determinations in one sample, the error in sampUng, 

 and also the difference in composition of the halves of the same potato. 

 The data show that the longitudinal halves of freshly dug sweet potatoes 

 have very nearly the same composition and that errors due to method 

 and technique are negligible. 



Table I. — Percentage composition of halves of freshly dug sweet potatoes 



No. of sweet potato. 



la. 

 la. 



lb 

 lb 



2a. 

 2a. 



2b 

 2b 



3a. 

 3a. 



3b 

 3b 



71-75 

 71.80 



71-23 

 71.29 



73-53 

 73-55 



74-47 

 74-32 



73-04 

 73.08 



73- 29 

 73- 14 



Reducing 

 sugar as 

 glucose. 



0.66 

 .66 

 .68 

 .68 



-79 

 .78 

 •75 

 •77 



.87 

 •85 

 .90 

 .90 



.94 

 •95 

 .98 

 .96 



I- 13 

 1-15 

 I. 16 

 I. 16 



I. 29 



1.32 



2. 27 

 2.23 

 2. 20 

 2.25 



2.17 

 2. 21 



1-95 

 1-93 



21. 00 



20. 99 



21. 00 

 20.9s 



21. 42 

 21.47 

 21.43 

 21-53 



19.58 



19.47 

 19.69 



19-55 



18.32 



18. 44 

 18.28 

 18.16 



19-59 

 19.78 



19. 60 

 19-58 



19- 33, 

 19-39 

 19. 21 



19-25 



