34 
BULLETIN" 1187, U. S. DEPARTMENT OF AGRICULTURE. 
The moisture determination on whole wheat is made according to 
the recommendations in the Handbook of Official Grain Standards. 
Preparation. — Standardize the heating time for making the moisture 
test as follows: Place 450 cubic centimeters of oil (the same as is 
used in the moisture test) into the flasks of each compartment of 
the tester. Insert the thermometer and regulate the mercury bulb 
so that the top is just flush with the surface of the oil. Connect 
the flasks with the condensing tube, replace the covers, light the 
gas, and note the time. Apply heat until the temperature of the oil 
reaches 175° C. and again note time. The time elapsed should be 
about 20 minutes. If more than 20 minutes is required to reach a 
temperature of 175° C, the holes in the bases of the burners should 
Fig. 26. — Ovens for making moisture tests. Vacuum ovens in foreground. Triple-walled electric oven 
in background. 
be opened; if less than 20 minutes the holes should be closed. The 
holes may be closed by lightly tapping the top of the base with a 
small hammer or any blunt instrument. They may be opened with 
a suitable reaming tool, such as a fine brooch, used by jewelers. 
Trial tests should be continued until the required time for heating 
all compartments does not vary more than one-half minute from 
20 minutes; that is, not less than 19^ minutes nor more than 20^ 
minutes, should be necessary to raise the temperature of the 450 
cubic centimeters of oil to 175° C. If a gas-pressure regulator is 
used, a uniform heating time is assured. If, however, this instru- 
ment is not available, it will be necessary for the operator to fix 
in his mind the flame necessary to heat the tester in the proper time, 
and, in case the gas pressure varies, to compensate for this by ad- 
justing the keys and air valves at the base of the burner. 
