2l8 



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- 



