asphaltum (asfaltum)

[NL.: see asphalt.] One of the so-called bituminous substances which are widely diffused over the earth, and are of great practical importance. See bitumen and bituminous. The asphaltums of various localities differ from each other considerably in chemical composition, as is proved by their different chemical reactions. They all agree, however, in being amorphous, in having the luster and general appearance of pitch (whence the name of min eral pitch, often applied to them), in melting at about the temperature of boiling water, and in taking fire when heated and burning with a bright but smoky flame. They differ e entially from coal in being more or le soluble in various reagents, such as oil of turpentine, ether, and alcohol. Asphaltum seems, in most cases at least, to have resulted from the hardening of the more liquid forms of bituminous substances, namely, maltha and petroleum, which have oozed out upon the surface and become inspi ated by oxygenation or evaporation of their more volatile portions, or by both causes combined. The most interesting locality of asphaltum is the so-called "pitch lake" in the island of Trinidad, about a mile and a half in circumference, and filled with asphaltum, which near the shore is quite solid, but nearer the center, in places, is soft and bubbling. Most of what is called asphaltum consists of this material more or le mixed with sand or other mineral substances. Asphaltum is extensively used in a variety of ways, and especially for pavements, foot walks, and roofing. For this purpose the material is prepared by mixing it while hot with sand or fine gravel, or by causing it to be absorbed by paper. Certain kinds of asphaltic rock, or asphalts (F. asphalte ), as they are frequently called, are peculiarly adapted for pavements or other special purposes. The localities of Sey el in France and de Travers in Switzerland are the most important of this kind. At each of these the asphalte consists of limestone impregnated with bituminous material to the amount of from 4 to 16 per cent. This rock, especially that from Val de Travers, has the remarkable prop erty of forming, without any admixture, an extra ordinar i ly durable and elastic roadway, and is, although expensive, extensively used for that purpose in Paris and other large cities of Europe. The rock has only to be heated, when it crumbles to powder, in which condition it is compre ed in molds into blocks, or simply spread over the surface required to be covered, and packed or pre ed by pestle or roller, when, after cooling, it a umes a condition closely resembling that of the original rock. See maltha, naph tha, and petroleum. Also asphalt.