Content may be subject to copyright.This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publ... ...This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in [Reply to comments of A. K. Kapila. Physics of Fluids 18, 12 p1826 (1975)] and may be found at https://doi.org/10.1063/1.861071.