Nature and Constitution of Shellac: XI. Rates of Adsorption of Moisture by Shellac Films¹

Abstract

spaces as being continuous, anymore than we would necessarily expect them to be in the solid phase of a jelly. Undoubtedly a few of the channels have external openings on both sides since some varnish films show a definite porosity (1, 2, 3, 5, 8,9), but it is clear from the studies made that the pores which do exist are usually extremely fine (1). Swelling by various liquids may, however, produce a permanent increase in permeability since varnish films would be of the elastic type of gels. The adsorptive forces involved when a liquid or vapor