SAMPLING AND TESTING HIGHWAY MATEKIALS. 
53 
be made by a fixed, arbitrary, and closely defined method if the results obtained are 
to be comparable. 
I. APPARATUS. 
(2) The apparatus shall consist of the following: 
(a) A brass ring 15.875 mm. (f inch) in inside diameter and 6.35 mm. (J inch) 
deep; thickness of wall, 2.38 mm. (-^ inch) permissible variation on inside diameter 
and thickness of ring, 0.25 mm. (0.01 inch). This ring shall be attached in a con- 
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venient manner to a No. 15 B. & S. gauge brass wire (diameter 1.79 mm. =0.0703 
inch). (See fig. 29.) 
(b) A steel ball 9.53 mm. (| inch) in diameter weighing between 3.45 and 3.55 
grams. . 
(c) A glass vessel, capable of being heated, not less than 8.5 cm. (3.34 inch) in 
diameter by 10.5 cm. (4.13 inch) deep. (A 600 c. c. beaker, Griffin low form, meets 
this requirement.) 
(d) A thermometer which shall conform to the following specifications: 
Total length 370 to 400 mm. (14.57 to 15.75 inches). 
Diameter - 6.5 to 7.5 mm. (0.256 to 0.295 inch) 
TCnlh length " " ' not over 14 mm. (not over 0.55 inch). 
iulb SateterV::::::::: 4.5 to 5.5 mm. (0.177 to 0.215 inch). 
