DUST PREVENTION AND ROAD PRESERVATION. 33 
Section No. 8.- — Refined water-gas tar preparation— Surface treatment. 
During the spring of 1913 the first surface treatment began to 
lose its efficiency on this section and a number of small, shallow 
chug holes developed, particularly toward the north end. In order 
to prevent further deterioration, these were repaired with a light 
application of heavy refined coal tar and fine gravel. On September 
12, 1913, the section was given a surface treatment of the same trade 
product which was originally used, the analysis of which is shown 
in the following table: 
Table 32. — Analysis of refined water-gas tar l used in second surface treatment of sec- 
tion No. 8. 
Specific gravity 25°/25° C 1. 120 
Viscosity, Engler, 50° C, 50 c.c. specific 12. 8 
Per cent of free carbon 0. 95 
Distillation: By volume. By weight. 
Water per cent. . 0'. 2 0. 2 
First light oils to 110° C do ... . .2 .2 
Second light oils 110°-170° C do ... . 2 1. 3 1. 
Heavy oils 170°-270° C do 2 23. 20. 5 
Heavy oils 270°-315° C do ... . 2,17.8 16. 2 
Pitch residue do 57. 5 61. 8 
Total.. do.... 100.0 99.9 
The surface was swept and the material was applied by an auto- 
mobile distributor and was charged at 9 cents per gallon distributed on 
the cleaned road. The application was immediately covered with 
clean limestone screenings of a size that would pass a 1-inch screen, 
and lightly rolled. The cost data for this treatment are given in 
Table 34. The section now offers a fairly uniform, attractive surface, 
well bound and comparatively free from ruts or depressions. 
Section No. 9. — Asphaltic petroleum — Surface treatment. 
This section, like section No. 8, began to lose the effect of its first 
treatment in the spring of 1913. The deterioration was most marked 
on the outer third of the road adjacent to the gutter, where traffic 
was lightest. This was evidently due to the fact that the surface 
lacked the ironing action of traffic and, lying somewhat open and 
porous, was rutted by the combined action of water and detritus- 
which worked over upon it. A number of shallow, worn depressions 
developed, principally at the south end of the section. These were 
filled by applying a hot paint coat of the oil asphalt used in section 
No. 5 and then filling the depression with clean 1-inch limestone 
screenings. 
On July 30 and 31, immediately after these patches had been made, 
the entire section was given a surface treatment of the same trade 
i Sticky, fluid. 2 Clear. 
