DUST PREVENTION AND ROAD PRESERVATION, 1915. 49 
Table 48. — Analysis of refined coal tar used on experiment No. 1. 
Specific gravity 25°/25° C 1.205 
Float test at 32° C. (time) V 48" 
Float test at 50° C. (time) 0' 46" 
Per cent free carbon (insoluble in CS 2 ) 12. 65 
_. . Percent Percent 
Distillation: by vol. bywt. 
Water 0.0 0.0 
First light oils (to 110° C). x .5 .3 
Second light oils (110° to 170° C.) 2 . 7 .5 
Heavy oils (170° to 270° C. ) 3 17. 1 15. 4 
Heavy oils (270° to 315° C.) 4 13. 7 11. 8 
Pitch residue 5 68. 72. 
Total 100. 100. 
Over the extended area of the experiment the surface is already 
broken in a great many places. Initial weaknesses, which developed 
over this section when a part of experiment No. 2, are persistent, and 
much patching has been necessary since a few weeks after the re-treat- 
ment in July. The failures are generally distributed over the surface 
and not confined to any strip. This section has an exceedingly heavy 
traffic, and during the winter is usually very dirty, owing to the bad 
condition of the lanes and adjacent roads which deliver traffic to the 
section. 
The section of this experiment in Bradley Lane has been recon- 
structed as penetration macadam, and is described as a new experi- 
ment in another part of this publication. 
Experiment No. 2. — Refined Water-Gas Tar, Cold Application. 
Those sections referred to in the last report, from Norwood trolley 
station to Edgewood station, as being poorly drained and under 
considerable strain, became so bad in the spring of 1915 that at the 
time of re-treating experiment No. 1 with a hot refined coal tar 
it was decided to extend the re-treatment northward to include the 
weak part of experiment No. 2. 
That part of No. 2 remaining is now in first-class condition. The 
general failure, especially along the edges, that was so rapid in the 
early spring of 1914, had no counterpart in the spring of 1915, and 
during the winter of 1915-16 the experiment has remained in excellent 
condition. While there are no indications of general failure, the 
mat is becoming very thin, and it is planned to give a re-treatment 
during the summer of 1916. The section of this experiment in Bradley 
Lane has been reconstructed as a penetration macadam and is 
described as a new experiment in another part of this publication. 
i Solid. 2 Clear. 3 One-third solid. * One-fourth solid. & Hard, brittle. 
