46 BT7LLETIX 586, IT. S. DEPARTMENT OF AGRICULTURE. 
station 2-f 44 to the end of the experiment, a crude-oil seal coat was 
applied and the pitting somewhat reduced. At approximate sta- 
tion 3+40 a mark across the experiment, which appeared to be a 
heavy lapping was very noticeable and considerable pitting occurred 
on both sides of it. 
Experiment Xo. 4 — Residual asphaltic petroleum, 1.4 gallons , pene- 
tration metltod. — A noticeable line at approximate station 4 + 15 dis- 
tinguishes the two parts of the first section of this experiment. The 
first part showed little tendency to pit where the mat was entirely 
gone and the sand mortar tended to wear away from around the stone. 
The mat was approximately 60 per cent intact on this section. On 
the second part of this section the mat was three-fourths gone and 
the aggregate exposed had a mosaic appearance. The sand mortar 
generally wore from around the stone. Section 2 of this experiment 
had a mat of a dead drab appearance more generally intact than that 
of section 1. The section showed a slight tendency to pit. 
Experiment Xo. — Oil asphalt, 1.8 gallons, penetration method. — This 
section continued to show little change in appearance, except that the 
wear on the mat was marked by lateral streaks, which may indicate 
application lines. There was some tendency to pit where the mat was 
gone entirely. A plug hole at approximate station 6-1-14, about 4 
feet from the right side, showed a very little tendency to ravel. 
Experiment Xo. 6 — Oil asphalt. 1. gallons, penetration method. — This 
experiment was in practically perfect condition, except for normal 
wear. 
Experiment Xo. 7 — Coralline rock, vjater-bound macadam. — This 
experiment showed considerable wear, approximating one-fourth inch 
in depth generally over the whole surface and 2 inches or more over 
most of the cross section for a distance of several feet from its junction 
with experiment Xo. 6. 
MIAMI, FLA., 1913. 
OIL-CORALLINE ROCK. 
The original report of these experiments appeared in Bulletin Xo. 
105, U. S. Department of Agriculture, and subsequent reports of 
several inspections in Bulletin Xos. 257 and 407. The following 
report is based on inspections made on April 24 and December 22, 
1916. During April a sewer trench was cut through the experimental 
sections. An examination of the surfaces at that time showed section 
Xo. 3 to be in fairly good condition. Sections 4 and 5 were failing 
and in a very poor condition. The bituminous material showed a 
penetration of from three-fourths to 1 inch. Section 6 was in excel- 
lent condition and showed no signs of local failures or undue wear at 
any point. The bituminous material showed a penetration of from 
lh to If inches. 
