THEaniline point (1) of a petroleum product is defined by the American Society for Testing Materials as the minimum equilibrium solution temperature for equal volumes of aniline and the petroleum product. The method of test (/) for determining the aniline point proposed by the A. S. T. M. depends upon the visual observation of turbidity in the mixture, and the test is intended for examination of oils not darker than No. 8 A. S. T. M. color (I). The aniline points of darker oils must therefore be determined by other means.Methods for determining the aniline point of dark oils are described by Bonn ($) and by van Wijk and Boelhouwer (4).