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 split dorsi- 
ventrally as nearly as could be judged. While one half was being pre¬ 
pared for 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 likely to 
occur in duplicate determinations in one sample, the error in sampling, 
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. 
ia. 
xa. 
ib 
ib 
2a. 
2a. 
2b 
2b 
3 a - 
3 a - 
3b 
3b 
Moisture. 
71* 75 
71. 80 
71 * 23 
71. 29 
73* 53 
73* 55 
74* 47 
74* 32 
73* 04 
73.08 
73* 29 
73* i4 
Reducing 
sugar as 
glucose. 
Cane sugar. 
Starch. 
0. 66 
2. 27 
21. 00 
.66 
2. 23 
2a 99 
.68 
2. 20 
21. 00 
.68 
2. 25 
20.95 
• 79 
2. 17 
21. 42 
.78 
2. 21 
21. 47 
• 75 
2. 21 
21.43 
•77 
2.25 
21. 53 
.87 
2. OI 
19. 58 
•85 
2. OO 
19* 47 
.90 
i* 95 
19. 69 
.90 
I * 93 
19* 55 
•94 
1* 95 
18. 32 
*95 
2. 03 
18 . 44 
.98 
2. 00 
18. 28 
.96 
2. 01 
18.16 
1. 13 
1. 74 
19* 59 
i* 15 
1. 68 
19.78 
1. 16 
1. 68 
19. 60 
1.16 
1. 60 
19.58 
19-33 
19*39 
1. 29 
1. 71 
19. 21 
1.32 
1. 66 
r 9* 25 
