Studies on crystal semi-permeable membrane. I. On the formation of the semi-permeable membrane of calcium carbonate.

present for the formation mechanism. A famous •gPfeffer's semi-permeable membrane•h made of potassium ferrocyanide and copper sulfate in unglazed pottery cylinder by W. Pfeffer in 1877 is quite different from an artificial semi-permeable membrane at present, which is organized only by handling of extending high molecular substances, that is, collodium, cellophane, and various synthetic resins. No semi-permeable membrane made directly of low molecular substances has been so far experimentally reported. Even the Pfeffer's membrane is, therefore, apt to be thought a semi-permeable membrane of high molecular substance. In 1942, however, Miyamoto and Takikawa1) discovered that a semi-permeable membrane was formed in an equilibrial state of the so-called Pringsheim's law, in the case of which magnesium chloride or calcium chloride was overlaid on agar, with sodium silicate. Accordingly magnesium chloride solutions with various concentrations as an external electrolyte were overlaid on agar gel made in testtubes which included sodium silicate as an internal electrolyte, at the time of which the silicate layer proceeded for the inner part of lower gel with a border surface as a base between the agar gel and the solution, in the case of the external electrolyte comparatively larger in concentration than the internal, and on the contrary in the smaller case, the layer proceeds for the upper solution. In the intermediate case between them, however, there exists an equilibrium point, where there is little permeation because the precipitate forms a thin membrane on the border surface. In despite that pigment accidentally