SAMPLING AND TESTING HIGHWAY MATERIALS. 
63 
The pressure of the gas shall be sufficient to prevent separation 
of the mercury column at all temperatures of the scale. There 
shall be a reservoir above the final graduation large enough so 
that the pressure will oot become excessive at the highest tem- 
perature. The thermometer shall be finished at the top with a 
small glass ring 01 button suitable for attaching a tag. Each 
thermometer shall have for identification the maker's name, a 
serial number, and the letters "A. S. T. M. Distillation.*' 
The thermometer shall be graduated from <>" to 400° C. at in- 
tervals of 1° C. Every fifth graduation shall bo longer than the 
intermediate ones, and every tenth graduation beginning at zero 
shall be numbered. The graduation marks and numbers shall be 
clear-cut and distinct. 
The thermometer shall conformTto the following dime ns: 
Total length, maximum: 385 millimeters. 
Diameter of stem: 7 millimeters; permissible variation. 
0.5 millimeters. 
Diameter of bulb, minimum. 5 millimeters, and shall not 
exceed diameter of stem. 
Length of bulb: 12.5 millimeters; permissible variation. 
2.5 millimeters. 
Distance from 0° to bottom of bulb: 30 millimeters: per- 
missible variation. 5.0 millimeters. 
Distance from 0° to 400° : 295 millimeters : permissible 
variation. 10.0 millimeters. 
The accuracy of the thermometer when delivered to the pur- 
chaser shall be such that when tested at full immersion the 
maximum error shall not exceed the following : 
From 0° to 200° 0: 0.5° O. 
From 200° to 300° C. : L0° C. 
From 300° to 375° C. : 1.5° C. 
The sensitiveness of the thermometer shall be such that when 
cooled to a temperature of 74° C. below the boiling point of water 
at the barometric pressure, at the time of test, and plunged into 
free flow of stream, the meniscus shall pass the point 10° C. be- 
Jow the boiling point of water in not more than six seconds. 
The thermometer shall be set up as for the distillation test, 
using water, naphthalene, and benzophenone as distilling liquids. 
The correctness of the thermometer shall be checked at 0° and 
100° C. after each third distillation until seasoned. 
(c) Condenser. — The condenser tube shall have the following Condenser. 
dimensions : 
Adapter : 70 millimeter-. 
Length of straight tube : 185 millimeters. 
Width of rube* 12 to 15 millimeters. 
Width of adapter end of tube : 20 to 25 millimeters. 
(d) Stand. — One iron stand with a universal clamp for hold- 
ing the condenser, and a light grip arm with a cork-lined clamp 
for holding the flask, shall be provided. 
(e) Burner and shield. — A Bunsen burner shall be provided. Burner. 
with a tin shield 20 centimeters long by '.» centimeters in diameter. 
The shield shall have a small hole for observing the flame. 
if) Cylinders. — The cylinders used in collecting the distillate Cylinders. 
shall have a capacity of 25 cubic centimeters and shall be gradu- 
ated in 0.1 centimeter. 
4. The apparatus shall be set up as shown in Figure 6. the ther- 
mometer being placed so that the top of the bulb is opposite the 
middle of the tubulature. All connections should bo tight. 
5. One hundred cubic centimeters of the dehydrated material t<> 
be tested shall be placed in a tared flask and weighed. After 
adjusting the thermometer, shield, condenser, etc.. the distilla- 
tion is commenced, the rate being so regular that 1 cubic centi- 
meter passes over every minute. The receiver is changed as the 
mercury column just passes the fractionating point. 
