METHODS OF SAMPLING AXD TESTING HIGHWAY MATERIALS 71 
(b) The cup proper shall be a 8-ounce Gill style con 55 millimeters in diameter 
and 3J millimeters in depth. The can shall be heated in a sand bath of a, 
diameter approximately ticice that of the can. The sand shall be about one- 
quarter inch deep beneath the can and an additional amount of sand shall he 
spread around the can so as to surround it to a depth of one-half inch. 
:'». The thermometer shall conform to the following requirements. These 
specifications cover a special thermometer graduated in either centigrade or 
Fahrenheit degrees as specified, the ranges being —6 to +400° C, or +20 to 
-4-760° F., respectively. 
Type : Etched stem, glass. 
Liquid : Mercury. 
Range and subdivision : —6 to +400° C. in 2° C. or +20 to +760° F. in 5° F. 
Total length: 303 to 307 millimeters (11.92 to 12.08 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, not 
over 13 millimeters (0.51 inch). Diameter, not greater than stem. 
Distance to —6° C. or 20° F. line from bottom of bulb. 40 to 50 millimeters 
(1.57 to 1.97 inches). 
Distance to 400° C. or 760° F. line from top of thermometer : 30 to 45 milli- 
meters (1.18 to 1.77 inches). 
Filling above mercury : Nitrogen gas. 
Top finish : Red glass ring. 
Graduation : All lines, figures, and letters clear cut and distinct. The first 
and each succeeding 10° F. line to be longer than the intermediate lines. Grad- 
uations to be numbered at each multiple of 20°. 
Immersion : 25 millimeters or 1 inch. The words " 1-inch immersion " on 
Fahrenheit thermometers or " 25 millimeters immersion on centigrade ther- 
mometers and a line around the stem 25.4 millimeters or 1.00 inch above the bot- 
tom of the bulb shall be etched on the thermometer. 
Special marking : "A. S. T. M. open flash," a serial number and the manu- 
facturer's name or trade mark shall be etched on the stem. 
Scale error: The error at any point of the scale when the thermometer is 
standardized as provided below shall not exceed 1° C. up to 372° C. or 2*4 ° F. 
up to 700° F. 
Standardization : The thermometer shall be standardized at the ice point and 
at intervals of approximately 100° F. for 25 millimeters or 1-inch immersion 
and for the following temperatures of the emergent mercury column : 
Average temperature of 
Thermometer reading : emergent mercury column 
100° C, 200° F 44° C. 110' F. 
150° C, 300 c F 54° C, 129° F. 
200° C. 400- F 64° C, 150 3 F. 
250° C. 500= F 77° C. 175° F. 
300° C. 600° F 91° C, 205° F. 
350° C, 700° F 108° C, 240° F. 
Test for permanency of range: After being subjected to a temperature be- 
tween 360° to 370° C. or 680° to 700° F. for 24 hours, the accuracy shall be 
within the limit specified. 
Case: The thermometer shall be supplied in a suitable case on which shall 
appear the marking: "A. S. T. M. open flash, —6 to +400° C." or "A. S. T. M. 
open flash, +20 to +760° F.," according to the type of thermometer. 
Note. — For the purpose of interpreting these specifications the following definitions 
apply : The total length is the over-all length of the finished instrument. The diameter 
is that measured with a ring gauge. The length of the bulb is the distance from the 
bottom of the bulb to the beginning of the enamel backing. The top of the thermometer 
is the top of the finished instrument. 
PROCEDURE 
4. (a) The thermometer shall be suspended or held in a vertical position by 
any suitable device. The bottom of the bulb shall be one-fourth inch (0.635 
centimeter 40 from the bottom of the cup, and above a point halfway between the 
center and back of the cup. 
(b) The cup shall be filled with the oil to be tested in such a manner that 
the top of the meniscus is exactly at the filling line at room temperature. The 
*■> The immersion line engraved on the thermometer stem will be one-sixteenth inch 
(0.159 centimeter) below the level of the rim of the cup. 
