Page:Popular Science Monthly Volume 61.djvu/224

218 trade names, with the solid residuum s from the ordinary distillation of petroleum, all of which are very unlike natural asphalts or any imitation of them in which natural bitumen is used and among which there is great diversity of properties and qualities.

To construct a street of any of these natural or artificial materials, all passing under the name of 'asphalt' the same general method of procedure should be followed.

If the crude asphalt is to be refined, it is put into an enormous