(1) The coagulation of silver halide sols which takes place when they were subjected to heating in an autoclave was studied. It was observed that the sols prepared by using an excess of potassium halide, especially the AgJ-sol in an excess of potassium iodide, were most stable against the action of heat. (2) The arsenic trisulfide sol from which hydrogen sulfide was removed shows noticeable coagulation at 180° and 200°C. This behaviour is quite different from that of the sol from which hydrogen sulfide was not removed. (3) The light absorptions of arsenic trisulfide sols, one which is free from hydrogen sulfide and the other containing hydrogen sulfide, were compared. No noticeable difference was observed.
The effect of size of powder and grain of carbide on the velocity of azotation was experimentally discussed, and it was also experimentally determined that the velocity of azotation of carbide at constant temperature and pressure is 1. proportional to the surface area of individual grains, in case of the “granular” carbide, and the radial velocity of azotation is constant at about 1140°C. or 2. the radial velocity is inversely proportional to the thickness of changed layer at 950°C. and lower temperatures. 3. In some cases, there are several types of character in the velocity.
The interfacial tensions between aqueous inorganic salt solutions and hexane have been measured by both statical and dynamical method. Results indicate that the interfacial tensions increase by the increase in concentration of the salt solutions, being nearly parallel to the surface tension of the salt solutions.