DUST PREVENTION AND ROAD PRESERVATION, 1915. 49 



Table 48. — Analysis of refined coal tar used on experiment No. 1. 



Specific gravity 25°/25° 1.205 



Float test at 32° C. (time) IMS'' 



Float test at 50° 0. (time) 0M6'' 



Per cent free carbon (insoluble in CS2) 12. 65 



^. .„ . Percent Percent 



Distillation: by vol. bywt. 



Water 0.0 0.0 



First light oUs (to 110° C) ^5 .3 



Second Ught oHs (110° to 170° C.) ^ _ 7 5 



Heavy oHs (170° to 270° C.) ^7.1 15.4 



Hea^^ oils (270° to 315° C.) n3. 7 11.8 



Pitch residue - ^ 68. 72. 



Total 100. 100. 



Over the extended area of the experunent the surface is aheady 

 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. Whde 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 hi another part of tliis publication. 



1 Solid. 2 Clear. » One-third solid. < One-fourth solid. ' Hard, brittle. 



