METHODS OF SAMPLING AXD TESTING HIGHWAY MATERIALS 97 
the balance be accurately made. The plummet can readily be made in the 
laboratory from a piece of ordinary glass tubing 7 millimeters in outside 
diameter, sealed at the end. and melting into the glass where sealed a short 
platinum wire. After cooling, place 9 to 10 grams of mercury in the tube, mak- 
ing a column 35 to 40 millimeters high. Seal off the tube within 20 millimeters 
of the top of the mercury column with blowpipe flame. The plummet shall 
have a length of a hunt 55 to 60 millimeters over all and shall weigh between 
10 and 12 grams. 
(b) SOLID AND SEMISOLID FRACTIONS 
14. A pan of the form shown in Figure 42, having the following approximate 
dimensions, may be used : 
Millimeters 
Diameter of base 20 
Diameter of top 25 
Depth 12 
Diameter of wire 1 
Total weight grams__ 7 
The pan and wires are made of platinum or nickel. 
15. Solid or semisolid fractions of oil which can not be readily liquefied can 
be rapidly and accurately tested in this apparatus by the usual method of weigh- 
ing in air and in water. The usual precautions of igniting 
the pan before use. and avoiding the inclosure of air or 
water in the sample, should be observed. 
Note. — The method for liquid fractions is usually applicable to 
the fractions 233° to 315" C. and the method for solid and semi- 
solid fractions to the fractions 315'- to ."..">." : < . 
FLOAT TEST OF RESIDUE 
16. The residue remaining in the retort after the distilla- 
tion test shall remain until it reaches a temperature be- 
tween 100° and 125° C. The consistency of the residue 
shall then be determined in accordance with the standard 
method of float test for bituminous materials (serial desig- f 1 -" — — 4 -Ag- 
nation D-139) of the American Society for Testing Mate- l\ / 1.2cm. 
rials (4). (See p. 74.) I* fl— * — 
Note. — Care must be taken at the end of the distillation test to H<--2«w.-»l I 
see That the vapor temperature as indicated on the thermometer H" 2.5cm. -^\ 
dop- not risp abov<- 355 c C. : an excess temperature of only 1° or 
2" C. at this point makes the float test invalid. 
COKE RESIDUE 
17. The coke residue of creosote oil shall be determined in 
accordance with the standard method of test for coke residue 
of creosote oil (serial designation D 168) of the American Fig. 42. — Platinum 
Society for Testing Materials ( ',) . (See below. . or mckel pan 
61. METHOD OF TEST FOR COKE RESIDUE OF CREOSOTE 
OIL 
(A. S. T. M. standard method (-}), serial designation D 168-27) 
1. Crucible. — The crucible shall be of platinum and shall have a capacity of 
20 to 30 cubic centimeters. The cover of the crucible shall be of the inverted 
type, having a depth of about 1 centimeter, the wall tightly fitting the crucible 
except for a slight crease. 
2. The residue resulting from the distillation test, carried out in accordance 
with the tentative method of test for distillation of creosote oil (serial designa- 
tion D 246-27 Tj of the American Society for Testing Materials (5) (see 
p. 98), shall be poured directly into the tared crucible or into a tin box wherein 
it may be heated on a water or steam bath, but not over a flame. About 1 gram 
of the residue shall be weighed into the covered crucible and then placed, on a 
platinum, nichrome, or fire-clay triangle over a Bunsen burner, with the bottom 
of the crucible 6 to 8 centimeters from the top of the burner. The burner flame 
shall be regulated to a height of 20 centimeters while burning free and the 
crucible shall be exposed to the full flame for seven minutes. A Meker burner 
may be usee}, or the crucible may be heated for several minutes in an electric 
104022°— 28 7 
