THE BROWN-DUVEL. MOISTURE TESTER 
9 
for this graduate are 7% inches high, nine-sixteenths inch inside 
diameter, with 1% inches of the top portion flared, to eleven-six- 
teenths inch in diameter, as shown in Figure 6. 
After each test the cylinders must be cleaned and dried, which 
can best be done with a swab or test-tube cleaner with a small 
sponge attached to on© end, as shown in Figure 7. Satisfactory 
cleaners can also be made as needed by twisting cotton 
waste, strips of cheesecloth, or some other similar sub- 
stance about one end of a piece of fairly heavy wire. 
If the graduate is not thoroughly clean, water from 
the following test will hang along the sides, making a 
correct reading exceedingly difficult; if the graduate is 
not thoroughly dry, the following test will of course 
show an inaccurate result. 
DISTILLATION FLASKS 
The distillation flasks, with a capacity of approxi- 
mately 1,000 cubic centimeters, should be made of the 
best grade of resistant glass and should be well an- 
nealed to withstand sudden changes in temperature 
without breaking. The necks of the flasks should be 
sufficiently heavy to stand tight corking. Figure 8 
shows one of these flasks in which the dimensions of the 
different parts are given in both centimeters and inches. 
Flasks showing wide* variations in the dimensions 
are useless. It is therefore recommended that in order- 
ing flasks it be definitely stated that they must be in 
accordance with the specifications given in this bulle- 
tin. In case the dimensions of the flasks, as well as 
other parts of the apparatus, are not approximately as 
herein specified, they should not be accepted or used. 
The most important points regarding the distillation 
flasks are the diameter of the flask, the dimensions of 
the neck, the distance from the bottom of the flask to m 
where the outlet tube is formed, and the angle of the lE'vi? 
outlet tube. If the distance from the bottom of the flask ^^ 
to the outlet tube is not correct, the flasks will not rest Fl( i\]-~r?, v :* h 
i /» ■, ' . ., for cleaning 
in the compartments of the tester in the proper manner. grad uated 
This condition makes it impossible to place on correctly cylinders n s 
the cover of the compartment. 
It is recommended that a plaster of Paris mold, as illustrated in 
Figure 9, be made of a flask of the proper dimensions and that all 
flasks be tested in this mold before being accepted from the manu- 
facturer. 
COPPER DISTILLATION FLASKS 
Numerous requests for information are received from time to time 
as to the advisability of using copper instead of glass flasks for mak- 
ing moisture determinations by the method described in this circular. 
The results of investigations by J. H. Cox, of the Grain Division, 
Bureau of Agricultural Economics, have shown that copper flasks 
may be used in the tester, although glass flasks have proved more 
satisfactory for careful work. In making moisture determinations 
70619°— 27 2 
