THE OIL CONTENT OF FLAXSEED 
31 
varied 0.3 per cent or more, the greatest variation in any sample 
being only 0.33 per cent. 
The method works equally well on linseed cake or meal, as will be 
seen by the data presented in Table 22, in which a comparison of 
the oil results obtained with 39 samples of linseed cake by the ether- 
extraction and by the optical method is given. With the linseed 
cake it was necessary to pass the material through a burr mill in 
order to grind it to a fine state of subdivision. For sake of uni- 
formity the linseed meal was also passed through a burr mill. 
Table 21. — Comparison of results obtained in determining oil content of linseed 
meal and cake by tlie ether-extraction and optical methods 
Sample number 
Per cent 
oil, ether- 
extract 
method 
Per cent 
oil, 
optical 
method 
Differ- 
ence 
Sample number 
Per cent 
oil, ether- 
extract 
method 
Per cent 
oil, 
optical 
method 
Differ- 
ence 
1. 
6.34 
6.33 
6.18 
6.34 
5.54 
6.50 
5.65 
6.51 
5.84 
5.75 
6.02 
5.82 
5.61 
5.53 
7.19 
6.84 
4.57 
5.61 
5.33 
5.79 
6.39 
6.31 
6.13 
6.13 
5.26 
6.27 
5.50 
6.50 
5.63 
5.45 
5.72 
5.41 
5.65 
5.42 
7.12 
6.60 
4.80 
5.30 
5.20 
5.73 
+0.05 
-.02 
-.05 
-.21 
-.28 
-.23 
-.15 
-.01 
-.21 
-.30 
-.30 
-.41 
+.04 
-.11 
-.07 
-.24 
+.23 
-.31 
-.13 
-.06 
21 
6.76 
6.04 
5.60 
5.37 
5.84 
5.53 
6.48 
6.83 
6.36 
7.96 
5.06 
5.86 
6.12 
6.29 
7.93 
8.55 
7.40 
6.13 
8.11 
6.60 
6.12 
5.17 
5.25 
5.80 
5.45 
6.40 
7.00 
6.10 
7.78 
4.89 
5.82 
. 6.28 
6.20 
7.70 
8.23 
7.32 
5.97 
8.28 
—0. 16 
2 
22 
+.08 
3. 
23 
-.43 
4. 
24... 
-. 12 
5 
25 
-.04 
6 
26 _ 
-.08 
7 
27„ 
-.08 
8.. 
28... 
-.17 
9 
29 
-.26 
10 
30 
-.18 
11 
31 . 
-.17 
12 
32... 
-.04 
13.. 
33 
+.16 
14 
34 
-.09 
15 
35... 
-.23 
16 
36 
-.32 
17.. 
37 
-.08 
18 
38 
-.16 
19 
39 
+.17 
20. .. 
1 Plus sign indicates greater percentage by optical method, 
by ether-extract method. 
Minus sign indicates greater percentage 
Comparison of the data obtained by using the two methods shows 
an average difference of 0.16 per cent. Greater differences were 
obtained with the meal than with the ground flaxseed. No doubt 
this was due to the smaller quantities of oil in the cake, making the 
reading by the optical method more difficult to carry out. 
SPECIAL POINTS FOR CONSIDERATION IN MAKING THE OPTICAL TEST 
FINENESS OF DIVISION OF SAMPLE 
As the method was being developed it was brought out that the 
seed had to be pulverized to a very fine state of subdivision before 
accurate results were obtainable. It was found that seed ground on 
an attrition mill was not in a satisfactory condition as it was too 
coarse for rapid and complete solvent action. Many trials were made 
with grinding devices of various kinds, and it was finally determined 
that a small flouring mill, having rolls 6 by 6 inches, corrugated 40 
to the inch, was the most satisfactory device for grinding flaxseed 
samples for analytical work. Such a mill reduces and pulverizes 
flaxseed without difficulty, to a point where over 80 per cent will pass 
through a 34 grits gauze in about four to five minutes. 
