32 S. F. Peckham — Petroleum in its 



The next step in the process is the addition to the refined 

 pitch of about 15 per cent of its weight of some heavy petro- 

 leum residuum, which renders the bitumen softer, and at the 

 same time may or may not dissolve both petrolene and asphal- 

 tene. The mixture is made complete by blowing air through 

 the melted mass for hours or even days. Sand is then added 

 to the bituminous cement until the bitumen is only equal to 

 10 per cent of the mass. To incorporate the sand with the 

 viscous mass, both are heated very hot and the sand and bitu- 

 men thoroughly mixed, when the mastic thus produced is put 

 in its place and rolled. 



Very great diversity is observed in the durability of the 

 mastic thus prepared and laid, and. to account for these diversi- 

 ties Mr. Clifford Richardson* would have us believe that it 

 depends on the excavation on the Island of Trinidad from 

 which the crude asphalt was taken. So too the Hon. Commis- 

 sioner of Public Works of the City of New York, by the 

 advice of Stevenson Towle,f Consulting Engineer, has reached 

 a similar conclusion. Speaking of the Eighth Ave. pavement, 

 a part of which "showed indications of disintegration" before 

 it was accepted Mr. Towle says, " the asphalt used in this work 

 was submitted by the contractor and. analyzed and approved by 

 chemical experts ;" and yet, farther on in this same report it 

 is stated that the asphalt was condemned because it was taken 

 from one excavation on the island rather than another. 



It is a very significant fact that an asphalt pavement should 

 show signs of disintegration within a few weeks of the time 

 of its having been laid. Especially is this the case when it is 

 considered that some of the most enduring constructions of 

 antiquity, which have withstood the ravages of time for at 

 least 3000 years, are constructions of asphalt. Modern con- 

 structions' of asphalt in Europe are said to remain intact for 

 more than twenty years. The asphalt pavement laid upon 

 Franklin Avenue in the City of Buffalo, has stood, with almost 

 no expense for repairs, for fifteen years and I do not believe 

 any one now knows from what exact spot the asphalt came. 

 It is a very well known fact however that the material 

 used to soften the asphalt was one that would dissolve both 

 constituents of the bitumen, and form a chemical union or 

 solution rather than a mechanical mixture with them. No 

 one knows how old the asphaltic sandstones are that contain 

 10 per cent of bitumen, but they do not disintegrate ; they 

 are solid, impervious and tough. 



* Report of the operations of the Engineer Department of the District of 

 Columbia for the fiscal year ending June 30. 1892, pp. 96-123. 



f Report of the Department of Public Works of the City of New York on 

 Street Pavements, with special reference to Asphalt Pavements. Thomas P. 

 Gilroy, Commissioner. 1892. pp. 9, and 11 et seq. 



