A MODERN STREET. 217 



than 20 years old. and in fairly good condition. A better imitation, or 

 what was supposed to be a better one, was made of pitch from the cele- 

 brated pitch lake of Trinidad and the liquid residuum of the petroleum 

 stills, which was then a drug on the market. ' This mixture was tem- 

 pered with sufficient sand to make about 90 per cent, of the mineral 

 matter and laid, spread and rolled like the European asphalt. The 

 experiment proving a success, the name 'asphalt street' was applied 

 to these artificial imitations of asphalt. Xo harm came from this 

 wrong application of M. Malo's word for many years, as the use of it 

 was confined to street surfaces of which natural bitumen was the 

 principal constituent. 



About 1890, the late Joseph D. Weeks, of Pittsburg, visited the 

 Pacific Coast and found that the petroleum refiners of California were 

 making a solid residuum from the distillation of petroleum and calling 

 it 'asphalt.' Mr. Weeks immediately conceived the idea that Cali- 

 fornia petroleum contained 'an asphaltic base,' or in other words, it 

 might be considered to be asphaltum dissolved in petroleum from 

 which it could be separated by distilling off the petroleum. This very 

 erroneous conclusion led to a second one, viz., that the residuum of the 

 distillation of California petroleum is practically the same thing as 

 natural asphaltum. On the contrary, these residuums of petroleum, no 

 matter in what manner they may be made, are the product of destruc- 

 tive distillation and should be made the subject of prolonged and care- 

 ful experiment before they are used in any considerable quantity as an 

 equivalent for natural asphaltum. 



The difficulty which M. Malo feared would follow the careless use 

 of terms to designate the different forms of bitumen has overtaken us, 

 inasmuch as the word 'asphalt' is now applied to a large number of the 

 most heterogeneous substances, quite unlike in many respects, but 

 having other properties, denominated bituminous, in common. 



An enumeration of these materials will illustrate my meaning. 

 The natural solid bitumens are M. Malo's asphalts, called in the 

 United States rock asphalt, and including bituminous sandstones, as 

 veil as limestones, of which there are large deposits in California, the 

 Indian Territory and Kentucky; Trinidad pitch; Bermudez, Cuban, 

 California, Mexican and other asphaltums; Gilsonite, the bituminous 

 coquina or shell limestone of Uvalde County, Texas, with the extracted 

 bitumens of California and the Indian Territory. All these materials 

 have been used successfully in making asphalt surfaced streets. 



The so-called artificial asphalts, called asphalts by local application 

 of the word, are the solid residuums of the so-called asphaltic petroleum, 

 found in California and Texas; Pittsburg Flux, which is the residuum 

 made by burning out the hydrogen from petroleum with sulphur; re- 

 siduums made by several other patented methods and sold under various 



