METHODS OF SAMPLING AND TESTING HIGHWAY MATERIALS 81 
skies of the flask, after which the residue shall be poured into a suitable recep- 
tacle and covered. If the residue becomes so cool that it can not be poured 
readily from the flask, it shall be reheated to a temperature not exceeding 125° 
C. by holding the bulb of the flask in a suitable bath and not by the applica- 
tion of flame. 
For weighing the receivers and fractions, a balance accurate to at least 0.05 
gram shall be used. 
(c) During the progress of the distillation the thermometer shall remain in 
its original position. No correction shall be made for the emergent stem of the 
thermometer. 
id) The results of the distillation test shall be reported in percentages by 
weight of water-free material. The following fractions are usually reported: 
Up to 170° c. 
17 Cr to 235° C. 
235° to 270 c C. 
270° to 300 e C. 
Residue 
53. METHOD OF TEST FOR SOFTENING POINT OF BITU- 
MINOUS MATERIALS (RING-AND-BALL METHOD) 
(A. S. T. M. standard method U), serial designation D 36-26, except as indicated. See 
p. 1; 
1. The softening of bituminous materials generally takes place at no definite 
moment or temperature. As the temperature rise>, they gradually and imper- 
ceptibly change from a brittle or exceedingly thick and slow-flowing material 
to a softer and less viscous liquid. F<>r this reason the determination of the 
softening point must be made by a fixed, arbitrary, and closely defined method 
if the results obtained are to be comparable. 
APPARATUS 
2. The apparatus shall consist of the following: 
(a I A brass riny 15.875 millimeters (five-eighths inch) in inside diameter and 
6.35 millimeter-? ( one-fourth inch I deep ; thickness of wall. 2.38 millimeters 
(three thirty-seconds inch) ; permissible variation on inside diameter and thick- 
ness of ring 0.25 millimeter (0.01 inch*. This ring shall be attached in a con- 
venient manner to a No. 13 B. & S. gauge brass wire (diameter 1.83 milli- 
meters=0.072 inch). (Fig. 33.) 
(&) A steel ball 9.53 millimeters t three-eighths inch) in diameter weighing 
between 3.45 and 3.55 grams. 
(c) A glass vessel, capable of being heated, not less than 8.5 centimeters (3.34 
inches) in diameter and measuring 10.5 centimeters (4.13 inches) in depth from 
the bottom of the flare. (A 600 cubic centimeter beaker, low form, meets this 
requirement.) 
(d) A thermometer which shall conform to the following requirements. 
Th-se specifications cover a special thermometer graduated in either centigrade 
or Fahrenheit degrees as specified, the ranges being —2 to +80° C. or +30 
to +180 F., respectively. 
Type: Etched stem, glass. 
Liquid : Mercury. 
Range and subdivision: —2° to +80° C. in 0.2° C. or +30° to +180° F. 
in 0.5 C F. 
Total length: 378 to 384 millimeters (14.88 to 15.12 inches). 
Stem : Plain front, enamel back, suitable thermometer tubing. Diameter, 6 
to 7 millimeters, (0.24 to 0.28 inch). 
Bulb: Corning normal or equally suitable thermometric glass. Length, 9 to 
14 millimeters (0.35 to 0.55 inch). Diameter. 4.5 to 5.5 millimeters (0.18 to 0.22 
inch). 
Distance to 0° C. or 32° F. line from bottom of bulb: 75 to 90 millimeters 
(2.95 to 3.54 inches). 
Distance to 80° C. or 176° F. line from top of thermometer: 30 to 45 milli- 
meters (1.18 to 1.77 inches). 
104022°— 2? 
