10 
BULLETIN 655, U. S. DEPARTMENT OF AGRICULTURE. 
mined in order to ascertain the relative rapidity with which the 
various oils dried to the customary film characteristic of drying oils. 
The drying tests were conducted by spreading a thin film of oil 
over ground-glass plates 2 inches square and allowing the film to dry 
by exposure to the air, due precaution being taken to prevent the 
accumulation of dust on the surface. The experiments were con- 
ducted indoors at ordinary room temperature during the winter and 
early spring months. 
Approximately the same weight (about 0.1820 gm.) of oil was 
used in every case, the oil spreading over an area of about 1^ square 
inches. The glass plates with the film of oil were weighed at definite 
intervals until no further increase in weight was observed, the time 
of complete drying being expressed in days. The average increase 
in the weight of all the oils varied from 12 to 14 per cent. 
Comparison of the drying tests in Table III shows that certain 
Cereal Investigations numbers at different stations produce oils which 
dry more rapidly or more slowly than others. 
Some stations show a close relationship among the Cereal Investi- 
gations numbers in the time of drying during the two seasons, while 
others show considerable variation in this respect. The effect of 
seasonal variation upon the composition of the oils at the stations 
is again evident. 
A study of this nature admits of two general comparisons, namely, 
(1) a comparison of the several Cereal Investigations numbers and (2) 
a comparison of stations with respect to the oils produced during the 
two seasons. 
In order that the data given in Tables II and III as related to the 
several Cereal Investigations numbers may be more readily compared, 
the yearly and general average yield, the specific gravity, the acid 
value, the iodin value, and the time of drying of the oils were com- 
puted and the results assembled in Table IV. 
Table IV. — Comparison of yield, specific gravity, acid value, iodin value, and time of 
drying of oils from the four flax varieties grown in 1914 and 1915. 
Yield of oil (per 
cent). 
Specific gravity. 
Acid value. 
Iodin value. 
Time of drving 
(days). 
Seed 
sample. 
Yearly 
> 
Yearly 
© 
> 
Yearly 
© 
> 
Yearly 
© 
> 
Yearly 
© 
> 
average. 
c3 . 
average. 
« . 
average. 
C3 . 
average. 
cs . 
average. 
e8 . 
cs M 
3 M 
rt cm 
a m 
C3 §0 
. 
•* 
to 
9 
-* 
U3 
a 
■* 
i« 
© lJ 
5 
a 
•■* 
"O 
c 
>-- 
© ^ 
c 
% 
Oi 
o 
2 
O) 
o> 
O 
2 
C5 
0.972 
0. 713 
o 
0.841 
4 
as 
161.3 
C". 
161.6 
O 
161.1 
3 
C5 
16.4 
2 
16.3 
C5 
16.35 
« 
No. 3.... 
34.59 
35. 65 
35.11 
0. 9281 
0. 9297 
0. 9289 
4 
No. 12.... 
32. 41 35. 29 33. 84 
3 
.9281 .9294 
.9287 3] .9751 .754 
.861, 2 162.5163.4 162.9 
116.1 
15. 15. 57 
3 
No. 13.... 
32. 67 33. 92 33. 22 
4 
.9284 .9300 
.9292 1! .940 .765 
.851 3160.4 162.6 161.5 
2 16.1 
14. 7 15. 43 
2 
No. 19.... 
35. 98 36. 79 36. 42 
1 1 
1 
.9276 .9295 
1 
.9285 41.10 .738 
1 I 1 
.920 1161. 7)159. 8.160. S 
1 I 1 1 
4 14.3 
1 
15. 7 15. 00 
1 
The yield of oil of the several Cereal Investigations numbers grown 
at all the stations during each season is strikingly constant. The rel- 
ative position of each number with respect to the average yield of oil 
