DUST PREVENTION AND ROAD PRESERVATION. 43 



Section No, 4. — Blast-furnace slag and repined coke-oven tar. 



The surface of this section is distinctly mosaic and it is rather 

 rough and uneven, particularly over the fill at the south end of the 

 section. The surface is, as a whole, firm, and about 80 per cent of it 

 is well bonded with tar which still shows considerable life. The 

 section has worn much less than those adjoining it and is now from 1^- 

 to 2 inches above them. 



Sections Nos. 5 and 6. — Blast-furnace slag. 



In general the surfaces of these two sections are about the same. 

 They are slightly dusty, with the No. 1 stone showing frequently, and 

 there were shallow ruts in the traveled way. In section No. 6 some 

 very large pieces of slag, apparently from 4 to 5 inches in diameter, 

 projected slightly above the surface and there were five shallow worn 

 places on the east quarter. 



Section No. 7. — Blast-furnace slag and open-hearth slag. 



This section presented the same general surface as sections Nos. 5 

 and 6. About 100 feet from the south end of the section the road has 

 sunk from 3 to 4 inches over a tile cross drain. 



SUPPLEMENTARY REPORT OF EXPERIMENTS MADE AT NEWTON, MASS., 



1908. 



ASPHALTIC PREPARATIONS, TAR PREPARATIONS, RESIDUAL OIL, AND MOLASSES-OIL- 



LIME. 



The original report of these experiments was published in Circular 

 No. 90, and reports of annual inspections were given in Circulars Nos. 

 92, 94, 98, and 99. No repairs have been made during the past year 

 and the following report covers an inspection made' on December 13, 

 1913. 



Experiments Nos. 1, 2, 3, 4, 5, 6, and 7. — Asphaltic preparation — Mixing 



METHOD. 



The surfacing of experiments Nos. 1 to 4, inclusive, was gradually 

 disappearing, and the west half of experiment No. 5 had deteriorated 

 seriously during the past year. There had been little change in the 

 condition of experiments Nos. 6 and 7, excepting for the fact that 

 the holes reported at the last inspection had slightly increased in 

 area during the year. In experiment No. 7 two additional holes, 

 each about 1 square foot in area, had developed. These are in the 

 wheel tracks and will continue to enlarge. 



Experiment No. 8. — Residual petroleum — Mixing method. 



This section had not changed appreciably since it was inspected a 

 year ago, excepting for the fact that eight small pits were developing. 



