EXAMINATION OF BITUMINOUS ROAD. MATERIALS, Sia: 
cover 6. A copper jacket c, 44 centimeters in diameter at the top 
and 21 centimeters long, is held in the neck of the bell jar by means 
of a rubber stopper d, and fits into the upper portion of the rubber 
stopper 7. A glass filter tube e¢ fits mside the copper jacket, and to 
prevent circulation of air and condensation of water between it and 
the jacket, a strip of heavy blotting paper fis wrapped around the | 
top of the filter tube. Just below the constriction in the filter tube 
a wad of absorbent cotton gis placed, tightly compressed to a length 
of 2 centimeters by means of a glass rod. Above this is a wad of 
tightly packed asbestos wool h, about 5 millimeters in length, upon 
which an asbestos filtermg mat 7 is prepared. The filter tube 
passes through a rub- 7 
ber stopper 7 into a 
vacuum filtering flask 
k of 500 cubic centi- 
meters capacity. The 
rubber stopper 7 is 4 
placed as tightly as %& 
possible against the 
neck of the bell jar, 
but to insure that 
there is no circula- 
tion of air, a disk of © 
blotting paper 7 is 
compressed between 
them. The thermom- 
eter m is capable of cL, = 
recording temper a- ibe ep] oe ee 
tures from —25° C. 
to 0° C. and has the 
—20° C. graduation at least 14 centimeters from the bulb. It is 
supported by means of a guiding cork n and. cork disk 0, which is 
held tightly against the top of the filter tube by the clamp >. 
The bell jar is filled with a freezing mixture of ice and salt in the 
proportion of three to one, which as it melts is drawn off through 
the bent glass tube g, which is fitted with a rubber connection r 
and pinchcock s and coliected in the 500 cubic centimeter filtering 
flask #. The apparatus is supported on the ring u and condenser 
clamp v, attached to the stand w. 
In separating the paraffin scale the following procedure is carried. 
out. The filtering flask k is removed and a small cork stopper 
inserted in the lower end of the filter tube to assist in retaining the 
solution to be chilled in the upper part of the tube. Ten cubic centi- 
meters of a mixture of equal parts Squibbs’ ether and absolute alcohol 
[> 
Is 
Fic. 16.—Apparatus for distillation in determination of paraffin scale. 
