40 
BULLETIN 13*75, U. S. DEPARTMENT OF AGRICULTURE 
secured by checking the results obtained with the moisture tester 
against results obtained by making moisture determinations by dry- 
ing to constant weight in the common type of double-walled oven 
filled with water maintained at the boiling point, except that the 
treatment for flaxseed is determined by checking with samples dried 
to constant weight in a 28-inch vacuum at a temperature of 99 to 
100° C. 
To determine the proper extinguishing point for the Brown-Duvel 
method, the following procedure takes place : 
In the case of corn, the grain is heated in a water- jacketed oven 
at the temperature of boiling water, 99° to 100° C, until no further 
loss of weight occurs in 24-hour intervals. This usually takes about 
96 hours. This loss in weight is considered moisture and is known 
as the standard moisture test. One hundred gram portions of the 
same grain are then treated in the Brown-Duvel way, the only vari- 
able being the temperature at which the flame is extinguished. The 
cut-off temperature is gradually changed through 5° or 10° units 
until the moisture test result by the Brown-Duvel method is the 
same as the moisture test obtained with the water-oven method. 
This temperature is then tried out in check tests on a large number 
of samples of corn having different moisture contents and further 
comparisons made with results as determined by the water-oven 
method. 
Table 13. — Comparison of the moisture machine method tests on a sample of 
corn at extinguishing temperatures of 160°, 170°, 180°, 190°, and 200° C. with 
oven test of the same sample 
Test No. 
Percentage of moisture 
Oven 
test 
Machine tests 
160° C. 
170° C. 
180° C. 
190° C. 
200° C. 
1 - - -- _ 
14.24 
14.21 
14 2? 
12.4 
12.4 
12.3 
12.4 
12.5 
12.3 
12.8 
13.1 
12.9 
13.1 
13.1 
13.0 
13.6 
13.5 
13.6 
13.4 
13.5 
13.4 
14.0 
14.0 
14.1 
13.9 
14.2 
14.2 
14.8 
2 
14.8 
3 . 
14.6 
4 
14.5 
5 -. -- 
14.6 
6 
14.6 
Average.. ... 
14.24 
12.4 
-1.8 
13.0 
-1.2 
13.5 
-0.7 
14.1 
-0.1 
14.7 
+0.5 
Table 13 illustrates how the preliminary extinguishing tempera- 
ture was chosen for corn. 
The cut-off temperatures are varied and comparisons continue to 
be made with results obtained with the water-oven method until the 
correct extinguishing temperature is found and this temperature is 
finally chosen as the proper cut-off temperature. The extinguishing 
temperatures that have been established to date for various com- 
modities are listed in Table 14. 
To determine the proper cut-off temperature for any commodity 
for which the test is applicable but for which the cut-off temperature 
has not yet been determined, proceed in a manner similar to that 
described for determining the proper cut-off temperature for corn. 
