50 BULLETIN 407, U. S. DEPARTMENT OF AGRICULTURE. 
Experiment No. 3. — Asphaltic Petroleum, Cold Application 
During the winter of 1914 the surface cracked and crumbled in 
places as during the preceding winter, and in many places mud 
formed. This ironed out under traffic, but the mat was so thin and 
broken that a second re-treatment became necessary and was applied 
June 25 to 30, 1915. A short section at the north end was not 
finished until August 16-18. The work was done by hand, as described 
in the last report, using the same bituminous material originally 
applied and torpedo sand similar to that used on experiment 7. 
Table 49 shows the characteristics of the bituminous material used, 
and cost data will be found at the end of this report. 
Table 49. — Analysis of asphaltic petroleum used on experiment 3. 
Specific gravity, 25°/25° C 0. 932 
Flash point, °C 35 
Burning point, °C 70 
Viscosity, Engler, 50 c. c, at 25° C, specific 61. 9 
Loss, 5 hours, at 163° C, 20 grams, per cent 22. 94 
Float test of residue at 32° C, time 5' 53" 
Float test of residue at 50° C, time V 22" 
Percentage of total bitumen insoluble in 86° B. naphtha 13. 67 
Fixed carbon, per cent 7. 62 
Soluble in CS 2 (total bitumen), per cent 99. 90 
Organic matter insoluble, per cent 10 
Inorganic matter insoluble, per cent 00 
Total, per cent 100. 00 
This experiment is becoming rough on one hill, where frequent 
unusual repairs have had to be made, as described in an earlier 
report. Except for this the surface presents the same character- 
istics as it did a year ago. During cold weather the mat crumbles 
rather freely and at the first thaw mud is formed. If traffic is not 
too heavy and the mud is not displaced the surface mat is restored 
rapidly as the surface dries and generally assumes its corky nature. 
If the mud is displaced to any marked degree, as is very likely to 
happen if there is a snow storm followed by a thaw, then the mat 
is not restored along the wheel tracks and two broad, shallow ruts 
are the result. The stone is soon exposed along these ruts and dis- 
integration follows rapidly. At the time of inspection ruts had 
formed along about 200 feet of this experiment at the same point 
where they formed in the winter of 1914-15. 
It is planned to give this experiment a fourth application early 
in the season of 1916. Except as noted above, the surface is smooth 
and in essentially as good condition as at the time of construction. 
Experiment No. 4. — Residual Asphaltic Petroleum, Hot Application. 
This experiment continues to present the best appearance of any 
of those still carrying the original treatment. No re-treatment was 
necessary during 1915, but it is probable that one will be required 
