DUST PKEVENTION AND EOAD PEESERVATION, 1915. 
53 
Table 51 . — Analysis of asphaltic petroleum used on experiment No. 7. 
Specific gravity 25°/25° C 0. 958 
Flash point, °C 32 
Burning point, °C 81 
Viscosity, Engler, 25° C, 50 cc. specific 96. 8 
Loss 5 hrs. at 163° C. 20 grams, per cent 25. 57 
Float test on residue at 50° 0., time V 13" 
Per cent of total bitumen insoluble in 86° C. naphtha 5. 38 
Fixed carbon, per cent 3. 60 
Soluble in CS 2 (total bitumen), per cent 99. 90 
Organic matter insoluble, per cent 08 
Inorganic matter insoluble, per cent 02 
Total, per cent 100. 00 
Table 52. — Mechanical analysis of sand used on experiment No. 7. 
Per cent. 
Passing £-inch screen, retained on |-inch screen 10. 6 
Passing £-inch screen, retained on 10-mesh sieve 5.3 
Passing 10-mesh sieve, retained on 20-mesh sieve 10. 8 
Passing 20-mesh sieve, retained on 30-mesh sieve 9. 8 
Passing 30-mesh sieve, retained on 40-mesh sieve 13. 3 
Passing 40-mesh sieve, retained on 50-mesh sieve 12. 1 
Passing 50-mesh sieve, retained on 80-mesh sieve 20. 5 
Passing 80-mesh sieve, retained on 100-mesh sieve 5.3 
Passing 100-mesh sieve, retained on 200-mesh sieve 2.9 
Passing 200-mesh sieve 9. 4 
Total 100. 
The traffic census has been continued, regular counts being taken 
every 13 days. The point of observation was changed on June 26, 
1915, so as to give better control, and the period of observation was 
reduced to 16 hours. A tabulation of the maximum and average of 
each class of traffic for the period between June 26, 1915, and Febru- 
ary 28, 1916, is given in Table 53. Traffic south of the census sta- 
tion is on experiment No. 1, that north of the station is on experi- 
ments Nos. 2 to 7, inclusive. 
Table 53. — Volume and character of traffic on Rochville Pike at the north end of section 1. 
Vehicle. 
Sections 2 to 7. 
Section 1. 
Maximum. 
Average. 
Maximum. 
Average. 
North- 
South- 
North- 
South- 
North- 
South- 
North- 
South- 
bound. 
bound. 
bound. 
bound. 
bound. 
bound. 
bound. 
bound. 
18 
9 
8 
4 
30 
13 
16 
8 
9 
16 
5 
8 
18 
27 
8 
15 
22 
16 
7 
6 
59 
24 
25 
11 
10 
22 
3 
5 
15 
44 
5 
17 
1 
3 
1 
2 
7 
2 
3 
14 
3 
15 
6 
30 
2 
28 
1 
15 
6 
6 
15 
1 
19 
2 
7 
1 
18 
2 
25 
4 
4 
7 
7 
48 
78 
16 
17 
55 
71 
22 
21 
2 
2 
14 
5 
2 
74 
90 
24 
26 
88 
104 
35 
37 
381 
528 
117 
126 
442 
582 
163 
169 
26 
26 
15 
16 
63 
43 
31 
25 
10 
13 
3 
6 
17 
48 
7 
15 
Loaded 1-horse wagon 
Unloaded 1-horse wagon . . . 
Loaded 2-horse wagon 
Unloaded 2-horse wagon. . . 
Loaded 4-horse wagon 
Unloaded 4-horse wagon . . . 
1-horse pleasure vehicle 
2-horse pleasure vehicle 
Saddle horse 
Motor cycle 
Excessively heavy vehicle. 
Motor runabout 
Motor touring car 
Loaded motor dray 
Unloaded motor dray 
