Some Experiments 00 Hydraulic Brake Fluid　Hygroscopicity of Hexylene Glycol

摘要

Hygroscopicity is one of the important factors which are useful for estimations ofqualities of brake fluids. Hexylene glycol (2-methyl-2， 4-pentanediol) is well suited as aprincipal component of glycol-type brake fluid. In this paper， the hygroscopic property ofhexylene glycol is studied from many experimental standpoints， and the detai1s ofexperiments are also described.Solving an equation of diffusion， it has been shown that water vapours absorbed at freesurface of hexylene glycol are transferred into the liquid by not only diffusions but alsoconvections. And this result has been experimentally proved with the methods of shadowphotographs and the “Schlieren-methode" .