Abstract
In the course of some experiments on dialyzation, my assistant, Mr. C. W. Eberlein, called my attention to the fact that liquid in a colloidion bag, which was suspended in the air, evaporated, although the bag was tightly closed. At first we were inclined to ascribe it to evaporation through a small aperture at the top of the bag, but further experiments and especially the speed of evaporation soon forced us to the conclusion that the aqueous vapor is given off through the membrane, as though the water were suspended as a solid without any membrane present. This phenomenon we have named pervaporation. The speed of this pervaporation is so great that with ordinary heating facilities such as a Bunsen flame and electric heaters, it has been impossible to heat water in a collodion container to a boil.
Distillation by means of pervaporation we have called perstillation. When a dialyzable solute within the membrane container reaches saturation, it crystallizes on the outside of the membrane. This phenomenon we have named percrystallization. In order to show some of the possible uses of these phenomena, we described a number of experiments and discussed the theoretical considerations.
For details see April number, Journal American Chemical Society, 1917.
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