DUST PKEVENTIOISr AISTD ROAD PEESEEVATION, 1915. 27 



Table 27. — Analysis of coal-tar preparation ^ used on experiment No. 3. 



Specific gravity, 25725° C 1. 144 



Viscosity, Engler, 50 c. c. at 40° C, specific 10. 4 



Free carbon (insoluble in CS2) per cent 5. 53 



T^. .-.-, ,. Percent Percent 



Uistmation: by volume, by weight. 



Water 2^ g 1.6 



First Ugbt oils (to 110° C) K7 .4 



Second light oils (110° to 170° C.) 3 i_ q .6 



Hea^T oils (170° to 270° C.) 323.2 20.1 



Heavy oHs (270° to 315° C.) 3 io_ 2 8.9 



Pitch residue * 63. 1 68. 3 



Total 100. 99. 9 



AH but 500 linear feet of the road surface near the south end of 

 the section was in excellent condition to receive the surface treat- 

 ment. The section was thoroughly swept with horse-drawn rotary 

 sweepers, and the tar adhered uniformly to the surface rock without 

 the aid of hand brooming. After about 500 linear feet of surface 

 had been sprayed, the distributor was stopped and the gravel was 

 spread immediately to prevent the tar from flowing off the surface 

 over the shoulders. The tar preparation was shipped in a tank car, 

 which was placed 2| miles from the near end of section 3. 



Experiment No. 4. — Repined Water-Gas Tar, Cold Application, Similar to 

 Experiment No. 2 on Rockville pike. 



Location: Station 169+02 to station 226+20. 



Length: 5,718 feet. 



Total area: 9,530 square yards. 



Date of application: September 22 and 23. 



Temperature of tar: About 130° F. 



Table 28. — Analysis or refined water-gas tar used on experiment No. 4- 



Specific gra^dty, 25°/25° C 1. 132 



Viscosity, Engler, 50 c. c. at 50° C, specific 16. 2 



Free carbon (insoluble in CS2), per cent 0. 64 



_... ..,, . Percent Percent 



Distillation: by volume, by weight. 



Water 0. 0. 



First light oils ^0 110° C; .0 



Second light oils (110° to 170° C.) 2^5 i q 



Heavy oils H 70° to 270° C.) 3 21. 5 is. 9 



Heavy oils C270° to 315° C.) 2 jS. 13. 4 



Pitch residue ■» 62. 66. 6 



Total 100. 99. 9 



The surface of this section was in exceUont condition and no repairs 

 wore required. The experiment was conducted in aU respects like 

 experiment No. 3. The tar when delivered in the distributors from 



1 Thin fluid. 2 Clear. a cloudy. ■• Hard, glossy, semisolid. 



