The Movements of Floating Particles

Abstract

IN reply to Mr. Archdall Reid (March 19, p. 60) I should say that the effects which he describes are the natural behaviour of a contaminated surface. A greasy contamination of the right order of magnitude tends to spread itself uniformly over the surface. If when the liquid in the saucer sways over to one side, the surface layer went with it, the contamination would be concentrated upon that side and diluted upon the other. Such a displacement is resisted. The invisible surface contamination remains nearly equally distributed, and the fact is witnessed by the visible particles floating upon it.