Capillarity

Abstract

In Mr. W. B. Hardy's excellent “Historical Notes upon Surface Energy and Forces of Short Range” in NATURE of March 23, vol. 109, p. 375, he remarks that “the exact way in which the attractive forces act in causing the rise of fluid in capillary tubes and the spreading of fluid over solid and fluid surfaces is still obscure.” He evidently rejects all explanations by any Laplacean conception of molecular attraction. He probably holds that the explanation is to be sought in the modern electric theory of the constitution of matter, but that this theory has not as yet been developed far enough to throw sufficient light on the question. By the use of the term “attractive,” however, he restricts the inquiry to a limited class of forces in terms of which these phenomena are to be explained. It is just possible that this restriction may preclude the solution of the problem.