14 
BULLETIN 1375, U. S. DEPARTMENT OF AGRICULTURE 
high temperatures and resist the action of the oil. Stoppers con- 
taining a large percentage of pure gum are not desirable, as they 
soon swell and become unfit for use. Before attempting to put any 
of the glass parts through the holes in the rubber stoppers, they 
should be moistened with oil or water, thereby lessening the chances 
of breaking the tubes and cutting the 
2,/ C.fT). hands. A good grade of stopper 
should last through 400 tests. 
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OIL FOR THE MOISTURE TESTS 
In making moisture tests a good 
grade of mineral engine oil must be 
used. The oil must be free from water, 
should have a specific gravity of about 
0.9000, or 25° Baume, should have a 
viscosity at 20° C. of from 342 to 513 
seconds Saybolt. Its flash point in open 
cup should be between 350° to 400° F. 
Fire point should not be over 450° F. 
The higher the viscosity, the greater 
the danger of boiling over, and for this 
reason cylinder oils should not be used. 
AUTOMATIC OIL-MEASURING DEVICE 
The automatic oil-measuring device 
consists of a container to which is at- 
tached an automatic measuring gauge. 
The gauge must be sufficiently accurate 
to measure and deliver not less than 150 
cubic centimeters and not more than 
155 cubic centimeters of testing oil in 
one draft. The device is operated by 
an upward pressure of the neck of the 
flask against an automatic catch on the 
gauge. The cover for the container 
should have a strainer sieve for strain- 
ing all the oil used in the tests. One 
form of the device is illustrated in 
Figure 14. 
OIL-RECOVERY AND OIL-STORAGE CANS 
LThe oil-recovery and oil-storage cans 
) are made similar to 5-gallon milk cans. 
— f The storage can is equipped with a 
Fig. 13.— condenser tube standard faucet at its base. The oil- 
recovery can is supplied with a strainer funnel, the sides of which 
are made of heavy-weight tin. The hopper of the funnel should be 
12 inches in diameter at the top, 7 inches deep, with an opening 5% 
inches at the base. The collar should be 2% inches wide, having an 
outside diameter of 5% inches. A brass mesh filter screen of fine 
dimensions should be soldered over the opening of the funnel where 
the collar joins the hopper. The top edge of the funnel should be 
finished with a T 3 ^-inch roll. These devices are shown in Figure 15. 
70 cm. 
