METHODS OF SAMPLING AND TESTING HIGHWAY MATERIALS 87 
(&) The solvent used when testing bituminous materials derived from coal 
tar. water-gas tar. etc.. shall be a coal-tar naphtha or a light oil and shall con- 
form to the following distillation requirements, determined in accordance with 
the standard method of test for distillation of gasoline, naphtha, kerosene, and 
similar petroleum products (serial designation D 86) of the American Society 
for Testing Materials (4) - 
Ninetv-eight per cent shall distill between 248° F. (120° C.) and 482° F. 
(250° CO- 
SAMPLE 
8. The sample shall be thoroughly representative of the material to be tested 
and the portion of the sample used for the test shall be thoroughly representa- 
tive of the sample itself. Deviation from this requirement shall not be 
permitted. 
Note. — The difficulties in obtaining proper representative samples for this determina- 
tion are unusually great, so that the importance of sampling can not be too strongly 
emphasized. 
PROCEDURE 
9. When the sample to be tested contains less than 10 per cent of water, 
exactly 100 cubic centimeters of the material to be tested shall be placed inti 
the still or flask and thoroughly mixed with an equal volume of solvent by 
swirling, proper care being taken to avoid any loss of material. If the material 
is measured by volume, an accurate 100-cubic centimeter graduated cylinder 
shall be used and the contents transferred to the still by rinsing with one 
50-cubic centimeter portion of solvent followed by two successive 25-cubic centi- 
meter portions of solvent, the cylinder being allowed to drain each time. When 
the sample to be tested contains more than 10 per cent of water, the volume of 
material us*'d shall be decreased to that which will yield somewhat less than 
10 cubic centimeters of water. 
Note. — In special cases where the water content exceeds 10 per cent and it is not de- 
sirable to reduce the size of the sample to that which will yield somewhat less than 10 
cubic centimeters of water, a distilling-tube receiver graduated from to 25 cubic centi- 
meters may be used. This tube shall be graduated from to 2 cubic centimeters in 0.1 
cubic centimeter, from 2 to 5 cubic centimeters in 0.2 cubic centimeter, and from 5 to 25 
cubic centimeters in 0.5 cubic centimeter. 
The connections between the still or flask, trap, and condenser shall be made 
by means of tight-fitting corks as shown in Figure 35. When the metal still is 
used, a heavy paper gasket moistened with the solvent shall be inserted between 
the lid and flange before attaching the clamp. A loose cotton plug shall be 
inserted in the top of the condenser tube to prevent condensation of atmospheric 
moisture in the condenser tube. 
Heat shall then be applied and so regulated that the condensed distillate falls 
from the end of the condenser at the rate of from 2 to 5 drops per second. The 
ring burner used with the metal still should be placed about 3 inches above the 
bottom of the still at the beginning of the distillation and gradually lowered as 
the distillation proceeds. 
The distillation shall be continued at the specfied rate until no water is 
visible on any part of the apparatus except at the bottom of the tray. This 
operation usually requires less than an hour. A persistent ring of condensed 
water in the condenser tube shall be removed by increasing the rate of distilla- 
tion for a few minutes. 
10. The volume of condensed water measured in the trap at room temperature 
multiplied by 100 and divided by the volume of the sample used shall be the 
percentage of water and shall be reported as " per cent water by volume, 
A. S. T. M. method." 
ACCURACY 
11. The accuracy to be expected with this method is that duplicate determina- 
tions of water should not differ from each other by more than one division on 
the trap. 
56. METHOD OF TEST FOR PERCENTAGE OF RESIDUE OF 
DESIRED PENETRATION 
1. Fifty grams of the oil are placed in a 3-ounce deep seamless tin box : the 
box is placed in a sand bath and heated over a Bunsen burner. A thermometer 
