METHODS OF SAMPLING AXD TESTIXG HIGHWAY MATERIALS 95 
of water present shall be determined by the following method, and the water- 
free oil so obtained shall be used in the distillation test : 
Measure 200 cubic centimeter of oil in graduated cylinder, and pour into 
copper still, allowing the cylinder to drain into the still for several minutes. 
Attach lid and clamp, using a paper gasket slightly wet with oil around the 
flange of the still. Apply heat by means of the ring burner, which -hall be 
placed just above the level of the oil in the still at the beginning of the test. 
and gradually lowered when most of the water has distilled over. Continue the 
distillation until the vapor temperature, indicated by the thermometer with 
the bulb opposite the off-take "f the connecting tube, reaches 205° C. Collect 
distillate in separat->ry funnel. When the distillation is completed, and a clear 
separation of water and oil in the funnel has taken place, read the water by 
volume and draw off: and returu any light oil di-tilled over with the water to 
the oil in the still. The dehydrated oil from the still shall be used for the 
distillation test. 
5. The amount of water may be determined in accordance with the standard 
method of test for water in petroleum products and other bituminous materials 
(serial designation D 95) of the American Society fur Testing Materials 
I See p. S5. 1 w 
MATTER INSOLUBLE IN BENZOL 
Water Inlet 
■Water Outlet 
-Hook to Support Wire 
-Condenser 
■ Cap of Filter Paper or 
Alundum Ware 
■-■Filter Cup 
— Wire Support for 
Filter Cup 
6. (a) Extractor. — The extractor may be of the form shown in Figure 39 or 
any similar form in which the oil is subjected to direct washing by the 
boiling vapors of the solvent. 
i 6 ) Filtering medium. — The 
filtering medium may be either 
two thicknesses of S. & S. No. 
575 hardened filter paper. 15 
centimeters in diameter, ar- 
ranged in cup shap^ by folding 
symmetrically : or a 1 u n d u m 
thimbles, flat bottom. 30 by 80 
R. A. 98. If filter papers are 
used, prior to using they shall 
be soaked in benzol to remove 
any grease, dried in a steam 
oven, and kept in a desiccator 
until ready to be used. The 
filter-paper cup may be sus- 
pended in the extractor flask 
by a wire basket hung from 
two small hocks on the under 
surface of the metal cover of 
the flask. If the alundum thim- 
ble is used, it may be supported 
by making two perforations in 
the top of the thimble and sus- 
pending from the cover by Ger- 
man silver or platinum wires. 
7. Weigh 10 grams of dry oil 
in a 100-cubic centimeter beaker. 
Add about 50 cubic centimeters 
of pure benzol and transfer 
at once to the filter cup. The 
filter cup or thimble is previously weighed, ami the paper cup shall always 
be kept in a weighing bottle until ready for use. Wash out the beaker with 
benzol, passing all washings through the filter cup. and place latter at once 
in the extraction apparatus. Extractor shall contain a suitable quantity of 
pure benzol. Sufficient heat to boil the solvent shall be provided by mean-- of 
an electric heater or a steam bath. Continue the extraction until the descend- 
ing solvent is practically colorless, and remove the filter cup and dry in steam 
oven until all solvent is driven off: cool in desiccator and weigh. The balance 
used for this purpose should be accurate to 0.5 milligram. 
j<— dScm.—A 
Fig. 30. — Extraction flask 
44 This method is of partiular service where the determination of water only is in- 
volved and the dehydrated material is not to be used subsequently tor anal; - 
