Finely divided solids as emulsifiers part III

Summary

The authors have examined many inorganic solids like bentonite, carbonates, sulphates, sulphides, oxychlorides, phosphates, arsenates, and arsenites of metals, as emulsifying agents and found that they all give coarse emulsions but some of them give quite stable emulsions and may be useful for technical application. The bentonite stabilised emulsions are initially very fine and in one month the change in globule size is rather small but in the second month the deterioration is rather rapid due to some changes in its structure. Carbonates are far superior to sulphates, which have little or no emulsification property. There are distinct regions of maximum degree of dispersion brought about by precipitation at either very high or very low concentration of the solid. The finer the dispersion the better the emulsifying properties as is clearly seen in the case of bismuth oxychloride. The arsenates and arsenites of calcium and aluminium are very good agents. It may probably be due to the fact that slow hydrolysis produces gelatinous precipitate or fine particles of carbonates formed by the action of air. Emulsions stabilised by aluminium arsenite or calcium arsenate may be used as insecticides, as arsenic compounds are highly toxic to all forms of animal life.