BULLETIN 56, U. S. DEPARTMENT OE AGRICULTURE. 
120 c in less than 15 minutes, the flame should be turned down, 
so that the temperature will rise approximately 5 degrees a minute. 
If it takes more than 15 minutes to reach 120°, the flame may 
be turned up, so that the temperature will rise at the rate men- 
tioned. The temperature of the oil in the 
inner flask should rise from 120° to 150° in 
approximately 6 minutes. If the oil between 
the walls is not emptied and another test is 
made before the oil gets cool, the time required 
to reach 120° will be less than 15 minutes with 
a proper flame. 
W/HE !5A(JZ£-} 
METHOD OF FINDING THE PROPER TEMPERA- 
TURE. 
The proper temperature at which to extinguish 
the flame in the apparatus was found by check- 
ing duplicate samples in the common type of 
double-walled water oven that was 11 mches 
high, 11 inches wide, and 10 mches deep, outside 
dimensions, and having a 1-inch space between 
the outer and the inner wall for the water. 
The water in the oven was kept boiling by two gas flames and was 
kept at a uniform height. The different substances were allowed to 
remain in the oven until they came to a constant weight. 
Fig. 
. — Strainer for recov- 
the oil. 
Fig. 7.— Rubber stoppers, showing the effect of heat when tested in a copper flask, 
tested once, B 30 times, and Conce. 
Stopper A was 
POINTS TO REMEMBER. 
(1) Both in the inner flask and between the two walls 150 c. c. of 
oil should be used. 
(2) The thermometer hi the copper flasks can be easily adjusted 
by so placing the bulb of the thermometer in flour or meal that a thin 
coating is left upon it. The thermometer is put into the flask and 
