VIII. The Correlation of the Distillation Range with the Penetration of Creosote into Paper Strips

Abstract

Measurements of the penetration tensions in paper of a series of creosotes distilled from a single coal tar are reported (the penetration tension being the product of the surface tension and the cosine of the contact angle). It is found that these data conform to two equations: one, previously developed by others from theoretical considerations of the effects of variation in size and distribution of capillary pores upon the theoretical equation of flow, the other, an empirical relationship which is less difficult to apply in more practical problems where many data must be analyzed. The creosote-paper contact angles are shown to be zero or extremely small. Possible errors in the paper strip method are discussed and the importance of calibrating each strip with a reference liquid is demonstrated. The failure of Washburn's equation, which has received considerable attention in the field of fibrous penetration, is shown to be due to the neglect of the hydrostatic head term. The penetration tensions of these creosotes are unaltered by the presence of adsorbed water.