SAMPLING AND TESTING HIGHWAY MATERIALS. 
55 
eighths inch) apart. After each test the sample and transfer 
dish shall be returned to the water bath and the needle shall be 
carefully wiped toward its point with a clean, dry cloth to re- 
move all adhering bitumen. The reported penetration shall be 
the average of at least three tests whose values shall not differ 
more than four points between maximum and minimum. 
(&) When desirable to vary the temperature, time, and weight, 
and, in order to provide for a uniform method of reporting re- 
sults when variations are made, the samples shall be melted and 
cooled in air as above directed. They shall then be immersed in 
water or brine, as the case may require, for one hour at the tem- 
perature desired. The following combinations are suggested : 
At 0° C. (32° F.) 200 grams weight, 60 seconds. 
At 46.1° C. (115° F.) 50 grams weight, 5 seconds. 
FLOAT TEST FOR BITUMINOUS ROAD MATERIALS. 
(A. S. T. M. tentative method, serial designation, D 139-22 T, slightly 
modified. I 
I. APPARATUS. 
1. The float shall be made of aluminum alloy and shall be in p loat 
accordance with the following requirements : 
Minimum. 
Normal. 
Maximum. 
Weight of float grams. . 
Total height of float millimeters. . 
Height of rim above lower side of shoulder 
millimeters . . 
Thickness of shoulder do 
Diameter of opening do 
Height of rim above water with load of 
5.5 grams millimeters.. 
37.80 
34.0 
26.5 
1.2 
10.7 
7.0 
37.95 
35.0 
27.0 
1.4 
11.1 
8.5 
38.10 
36..0 
27.5 
1.6 
11.5 
10.0 
2. The collar shall be made of brass and shall be in accordance 
with the following requirements: 
Minimum. 
Normal. 
Maximum. 
Weight of collar grams. . 
Over-all height of collar millimeters. . 
Inside diameter at bottom do 
Inside diameter at top do 
9.9 
22.3 
12.78 
9.66 
9.95 
22.5 
12. SO 
9.68 
10.0 
22.7 
12.82 
9.70 
Colic 
to the following specifica- ThermmuUr% 
3. The thermometer shall conform 
tions : 
Total length: 370 to 400 millimeters (14.57 to 15.75 inches). 
Diameter: 6.5 to 7.5 millimeters (0.256 to 0.295 inch). 
Bulb length: Not over 14 millimeters (not over 0.55 inch). 
Bulb diameter: 4.5 to 5.5 millimeters (0.177 to 0.217 inch >. 
The scale shall be engraved upon the stem of the thermometer, 
shall be clear-cut and distinct, and shall run from 0° to 80° C. 
(32° to 176° F.) in 0.2° C. divisions. It shall commence not less 
than 75 millimeters (2.95 inches) above the bottom of the bulb. 
The thermometer shall be furnished with an expansion chamber 
at the top and have a ring for attaching tags. It shall be made 
of a suitable quality of giass and shall be so annealed as not to 
change its readings under conditions of use. It shall be correct 
to 0.25° C. (0.45° F.) as determined by comparison at full im- 
mersion with a similar thermometer calibrated at full immersion 
by the United States Bureau of Standards. 
4. The minimum diameter of the bath shall be twice the diam- 
eter of the float: the minimum depth of water shall be equal to 
the diameter of the bath. 
