Page:Popular Science Monthly Volume 81.djvu/37

Rh those which are soluble in light petroleum naphtha, and the remainder which are insoluble, although the percentage will depend to a certain extent on the character of the solvents. The softer or oily portion which is soluble in naphtha is, for 88° naphtha at air temperatures, about 63 per cent. The components of Trinidad asphalt and of other bitumens, which are thus soluble, have been denominated by the writer "Malthenes" a name to be applied to this class of hydrocarbons, not as representing any homogeneous entity, but merely descriptive of their general character. The term petrolenes has also been used to cover this same class of material.

The hydrocarbons and their derivatives which are insoluble have been called asphaltenes.

The malthenes of Trinidad asphalt are distinguished by the fact that they are of an extremely sticky and cementitious nature, and not merely oily as is often the case with material of similar consistency prepared from petroleums. The value of any bitumen or combination of bitumens for highway construction depends on the character of the malthenes of which it is composed, and the relative proportion of these to the asphaltenes. Where the former are not present in sufficient amount, it is necessary to add to the asphalt material in which malthenes predominate to attain a proper consistency. This is known as fluxing the asphalt, and in the case of that of Trinidad, owing to the presence of the large amount of malthenes of a sticky nature, it can be accomplished