THE FREEZING POINT OF POTATOES. 3 
tion of this term on p. 6) by tapping it sharply against the side of 
the freezing tube after it was undercooled to about 25° F. The 
true freezing point could then be found almost immediately. The 
freezing point was the same as though the potato had been allowed 
to undercool until self-inoculation took place. The whole operation 
from the time the section of the potato was inclosed in the freezing 
tube until the final freezing point was determined seldom took 30 
minutes. 
FREEZING POINTS OF DIFFERENT VARIETIES AND GROUPS OF 
POTATOES. 
Determinations of the freezing point were made at four periods 
(Feb. 12, Feb. 18, Mar. 5, and Apr. 1) on seven standard varieties of 
potatoes: Irish Cobbler, Triumph, Spaulding No. 4, Russet Rural, 
Rural New Yorker, Green Mountain, and American Giant. In 
addition, in the last period freezing-point determinations were made 
on 11 additional varieties: First Early, New Early Standard, Pro- 
ducer, Oregon White Rose, Early Prospect, Up-to-Date, Gold Coin, 
Ehnola, Garnet Chili, British Queen, and United States Seedling No. 
38774. These potatoes were all true to name and were all grown 
under the same conditions at the Aroostook Farm of the Maine 
Agricultural Experiment Station under the direction of William 
Stuart, of the Office of Horticultural and Pomological Investigations. 
On arrival at Washington they were placed in storage at 40° F. 
Duplicate determinations were made from at least two specimens 
of each variety. Generally, more were used ; in some cases as many 
as eight specimens. Table I presents the average results in Fahren- 
heit and centigrade of all the freezing-point determinations made. 
The relative position of each variety on the list at each successive 
date is also stated. Table II gives the freezing points of all 18 
varieties determined on April 1. These are arranged in varietal 
groups. 
Table I. — Freezing points and relative positions of seven varieties of potatoes on four 
successive dates. 
Feb. 12. 
Feb. 18. 
Mar. 5 . 
Apr. 1. 
Variety. 
Rel- 
ative 
posi- 
tion. 
°F. 
°C. 
Rel- 
ative 
posi- 
tion. 
°F. 
°C. 
Rel- 
ative 
posi- 
tion. 
°F. 
°C. 
Rel- 
ative 
posi- 
tion. 
°F. 
°c. 
Irish Cobbler 
1 
3 
5 
6 
4 
7 
2 
29.35 
28.77 
28.28 
28.16 
28.42 
28.13 
29.00 
-1.47 
-1.79 
-2.07 
-2.14 
-1.99 
-2.16 
-1.67 
1 
4 
3 
6 
5 
7 
2 
29.18 
28.48 
28.55 
28.32 
28.39 
28.22 
28.73 
-1.57 
-1.96 
-1.92 
-2.05 
-2.00 
-2.10 
-1.82 
1 
2 
3 
4 
6 
7 
5 
29.66 
29.38 
29.35 
29.16 
29.08 
28.86 
29.13 
-1.30 
-1.46 
-1.47 
-1.58 
-1.63 
-1.75 
-1.60 
1 
4 
3 
7 
5 
6 
2 
29.66 
29.04 
29.33 
28.32 
28.70 
28.50 
29.64 
—1.30 
Triumph 
— 1.56 
Spaulding No. 4 
-1.48 
—2.05 
Rural New Yorker 
Green Mountain 
American Giant 
-1.84 
-1.95 
-1.31 
