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Page:Popular Science Monthly Volume 81.djvu/38

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PSM V81 D038 Laborers quarters at point dor.png

Photo, C. R. Toothaker, Phila. Commercial Museum.

Laborer's Quarters, Point d'Or.

by the use of any of the fluxes that are available, even those of a paraffine nature, since the paraffine hydrocarbons, containing a considerable per cent, of paraffine scale, combine with the malthenes of the Trinidad asphalt to produce a satisfactory binding material. If the malthenes were not present to the extent in which they are found, it would be necessary to use an asphaltic flux, as for example in fluxing the harder bitumens, such as gilsonite and grahamite.

While the malthenes give to the asphalt its cementitious property, the asphaltenes impart cohesiveness as distinguished from adhesiveness, and supply body and stability to the binding material. It has been found that asphalt cement, that is to say, a solid asphalt combined with a suitable flux, must contain not less than 15 per cent, of asphaltenes or will otherwise lack cohesiveness and stability, while on the other hand, if it contains less than 70 per cent, of malthenes it will not be sufficiently adhesive. Even with the proper proportions of malthenes and asphaltenes a bitumen may still be valueless as a cement, if the malthenes are not of a proper character, that is to say, not sticky and adhesive.

Trinidad asphalt, owing to the character of and proportions in which its components are present, has been found to possess to the highest degree, the properties which are necessary for adhesiveness and stability, and it is to this that we may attribute the fact that it has proved itself to be a standard material with which to compare other bitumens.