Page:Popular Science Monthly Volume 61.djvu/224

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��POPULAR SCIENCE MONTHLY

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

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�� ��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 ket-

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