4 BULLETIN 257, U. S. DEPARTMENT OF AGRICULTURE. 
Experiment No. 2 (Ligut Om—PENETRATION MeETHOD). 
Location: Station 6-+35.8 to station 0+58.1—22.3 feet. 
Area: 44.6 square yards. 
Method.—This section was intended to be a part of experiment 
No. 1, but owing to the destruction of the barrel markings during 
storage, a kettle of the light oil was heated by mistake and applied 
here at an average rate of 1.12 gallons per square yard. It was 
entirely absorbed during a half hour’s standing, after which it was 
covered with sand and rolled. 
EXPERIMENT No. 3 (HEAVY Om—PENETRATION METHOD). 
Location: Station 0+58.1 to station 1+65.9=107.8 feet. 
Area: 215.6 square yards. 
Method.—The apparent failure of experiment No. 1 necessitated 
a return to substantially the same method as was used in experiment 
No. 6 at Miami, although the poor working conditions did not promise 
equal success. The application of hot bitumen was reduced to an 
average rate of 0.89 gallon per square yard. From station 0+58.1 
to station 1+ 39.0 the actual rate of application was 1.01 gallons per 
square yard. From station 1+39.0 to station 1+65.9 rains during 
the previous night had so bound the surface that the rate of applica- 
tion had to be reduced to 0.54 gallon per square yard, and little more | 
than a surface treatment was obtained. The sand was applied and 
rolled as usual. 
EXPERIMENT No. 4 (WaTER-GasS Tar PREPARATIONS—SURFACE TREATMENT). 
Location: Station 1+65.9 to station 1+95. 4=29.5 feet. 
Area: 59 square yards. 
Method.—Owing to the Soni eneres of the work from January 13 
to 29, this section of the road had become completely water bound by 
rains and heavy traffic. The surface was thoroughly swept with 
rattan brooms, and water-gas tar preparation No. 1 applied without 
heating at a rate of 0.25 gallon per square yard and allowed to 
stand for 24 hours. Water-gas tar preparation No. 2 was then 
applied at the rate of 0.42 gallon per square yard and allowed to 
stand for about four hours. By that time it appeared to have reached 
its maximum penetration and was covered with sand and rolled. 
By the use of the light tar preparation applied directly to the surface 
of the rock and followed by the heavier product, it was hoped to 
secure greater adherence of the bituminous surface than had pre- 
viously been obtained in strict surface treatment, and at the same 
time build up a comparatively thick wearing coat. 
EXPERIMENT No.5 (WaTeR-GAs Tarn PREPARATION—PENETRATION METHOD). 
Location: Station 1+95.4 to station 3+34.4=139 feet. 
Area: 278 square yards. 
Method.—The screened-rock course was constructed as usual, but 
by rescreening the rock the proportion of fine material was consider- 
