shown eignifimnt differences in the fractions of a n as1)hai.t when separated either by chromatography or by niolecular distillation. :\lore importantly, it has shown that straight reduced asphalts from 15 picked and identified crude sources have widely different structural characteristics. Because all of the asphalts listed have established satisfactory service qiialities, the latter d a t a seein t o point out that either widely varying structural vharacteristics can he tolerated or 0111' method for judging service chai-acteristics needs sharpening. If wrvire qualities of an asphalt could he placed on a rating then there is a good chance that ensiinetric charrtcterization could be used t o establish that nee relation between laboratory a n a service qualities. In The meantime, the
method is offered as a tool for identification or as a means for following changes in asphalt during nianufacture or in service. ACKNOWLEDGMENT
The author is intlebted to R. 13. Williams of Research and Develoliment, Humble Oil and Refining Co.. I3aytown, Texas, for his interpretation and inodific-ation of the original Van Krevelen method. It was through the work of Williams that this adaption of the densimetric technique was iiiade possible. LITERATURE CITED
(1) Corbet,t, 1,. Proc. Assoc.. .4sp. Pac. Tech. 23. 14 il954). ( 2 ) Corbett, L. IT-., Saarhrick, R . E., I
j
Ibid., 27, 107 (195S). ( 3 ) Ibitl., 29, 104 (1960).
(4) Grfinin,11. L., Simpstin, lV. C., Miles, T. I
