THE BROWN-DUVEL MOISTURE TESTER 39 
standard heating time is the same regardless of the sources of heat 
energy, whether gas, electricity, alcohol, or gasoline. 
If, on making a check test with the oil-test method, all heaters do 
not rise uniformly within one-half minute of 20 minutes, they are 
not standard and will give either high or low moisture-test results, 
and the services of a competent electrician are needed. 
To make an electric-heated machine check with the gas-heated ma- 
chine, the electric heaters of the box type in which the upper side is 
open, if they are giving a standard output of heat, should be lowered 
after making the moisture test. If they are not giving a standard 
amount of heat, direct comparison with a standard gas tester is the 
only way in which one can determine in what position the heater 
should be left. When that type of box heater is used in which the 
top and bottom casing of the box is absent, the heater should be left 
in position to assure check results with the gas-heated testers. If this 
type of heater is lowered from its operating position when the cur- 
rent is turned off, heat is lost too rapidly from the compartment after 
the completion of the test. 
The data obtained from these experiments show that the maxi- 
mum difference between the results obtained on an electrically-heated 
machine, properly adjusted and carefully operated, and on a stand- 
ard gas-heated tester should be very slight, with a voltage drop of 
not over 5 volts. Results, therefore, which are in excess of this are 
due to faulty operation of the machine, such as not waiting for the 
temperature of the oil in the flask to drop to 160° C. before making 
a reading; use of faulty equipment, including incorrectly gradu- 
ated thermometers or measuring cylinders and spongy rubber stop- 
pers ; inaccurate weighings, or lack of priming tests. 
TESTS WITH ALCOHOL AND GASOLINE BURNERS 
Moisture tests can be made with a Brown-Duvel moisture tester 
heated with alcohol or gasoline burners, but such tests can not be 
made with the satisfaction attending the use of gas or electric-heating 
units. In making tests with alcohol or gasoline burners, the flame 
is very irregular and needs frequent adjustment of the burner valves 
during the progress of the test. 
When the burners are used, they may be standardized by placing 
them at a distance of 2% inches from the wire gauze and the flame 
adjusted to a point where it will develop heat enough to raise the 
temperature of the oil and grain in the flask to 120° C. in 10 minutes 
and then to give a steady rise in temperature beyond this point of 
from 6° to 8° per minute, until the cut-off temperature is reached. 
HOW TO CHOOSE EXTINGUISHING TEMPERATURES 
The Brown-Duvel method has not yet been developed for testing 
a number of commodities for which the method is applicable. Ques- 
tions are frequently asked regarding the procedure necessary to de- 
termine the proper extinguishing temperatures for different com- 
modities. 
The extinguishing temperatures for testing the moisture content 
of various commodities with the Brown-Duvel moisture tester are 
