EXAMINATION" OF BITUMINOUS -ROAD MATEKIALS. 



33 



cover b. A copper jacket c, 4| 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 j. A glass filter tube e fits inside the copper jacket, and to 

 prevent circulation of air and condensation of water between it and 

 the jacket, a strip of heavy blotting paper/ is wrapped around the 

 top of the filter tube. Just below the constriction in the filter tube 

 a wad of absorbent cotton g is 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 Ji, about 5 millimeters in length, upon 

 which an asbestos filtering mat i is prepared. The filter tube 

 passes through a rub- 

 ber stopper j into a 

 vacuum filtering flask 

 Jc of 500 cubic centi- 

 meters capacity. The 

 rubber stopper j is 

 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 I is 

 compressed between 

 them. The thermom- 

 eter m is capable of 

 recording tempera- 

 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 o, which is 

 held tightly against the top of the filter tube by the clamp p. 



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 <[, which is fitted with a rubber connection r 

 and pinchcock .s and collected in the 500 cubic centimeter filtering 

 i'L k t. The apparatus is supported on the ring u and condenser 

 clamp v, ;ii tached to the stand vj. 



In separating the paraffin scale the following procedure is earned 

 out. The filtering flask k is removed and a small cork stopper 

 rted in. the lower cud 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 pads Squibbs' ether and absolute alcohol 



Fig. 10. — Apparatus for distillation in determination of paraffin scale. 



