Relations to Asphaltic Pavement. 31 



These researches show that the soluble and fluid portions of 

 bitumens are converted into insoluble and solid forms, that 

 may or may not contain oxygen, either by prolonged action of 

 air and other oxidizing agents at ordinary temperatures, or at 

 higher temperatures. They also show that the same effects 

 are produced without the action of reagents by prolonged 

 heating alone and the familiar process in technology known as 

 "cracking," is a further illustration of the tendency of bitu- 

 mens under the influence of heat alone, to break up into one 

 series of compounds richer than the original in hydrogen and 

 another compound or series of compounds richer than the 

 original in carbon. 



Now within a few years and since all of this work was com- 

 pleted, the laying of asphalt pavements has become an indus- 

 try involving the expenditure of vast sums of money and 

 consequently presenting technical problems of vast importance. 

 The technology proceeds about as follows : A quantity of 

 asphaltum is brought to New York from Trinidad. This 

 asphaltum consists of water, 27 per cent ; inorganic matter, con- 

 sisting of fine aluminous sand, 27 per cent ; organic matter 

 insoluble in carbon di-sulphide, 8 per cent ; bitumen 38 per 

 cent. This crude asphaltum is put into large open kettles and 

 melted, the temperature being raised and maintained for some 

 time in the neighborhood of 400° F. By this treatment the 

 water and lighter oils are expelled, and a portion of the mine- 

 ral matter sinking out of the melted mass to the bottom of 

 the kettles, a "refined pitch " is left, which is drawn off. This 

 "refined pitch," consists in round numbers, of 56 percent of 

 bitumen, 36 per cent of mineral matter and 8 per cent of 

 organic matter not bitumen. Of the 56 per cent of bitumen, 

 36 per cent is soluble in petroleum naphtha, leaving 20 per cent 

 that may be obtained from solution in carbon di-sulphide in 

 brilliant black scales. Properly interpreted the refined pitch 

 consists of : 



Petrolene . - 36 per cent. 



Asphaltene 20 per cent. 



Organic matter not bitumen.. 8 " 

 Mineral matter 36 " 



64 " 36 " 



64 per cent of material without cohesion ; that is, dry solids 

 for the most part, are held together by 36 per cent of a vis- 

 cous adhesive tar. The 20 percent of the asphaltene dissolves 

 in the petrolene, the remaining 44 per cent being simply min- 

 eral and organic matter held together by the combined bitu- 

 mens. 



