Salts, colloidal silver halides

The formation of colloidal silver halide dispersions (photographic emulsions) was reviewed as a model system of colloids which are formed by precipitation of sparingly soluble salts. For such systems, models for crystal nucleation and growth were derived which were verified for the AgBr system. These models can probably be extended to the study of nucleation and growth of other highly insoluble colloidal systems. 

Just as in the case of difficultly soluble metals, sulfides, and oxides, almost all other insoluble bodies may be obtained in the colloidal form. Of importance are the colloidal salts, which may be prepared either as hydrosols or hydrogels. Graham obtained colloidal copper ferrocyanide by dissolving the brown precipitate in ammonium oxalate, and subsequent dialysis. He also prepared colloidal Prussian blue by a similar method. Schneider f obtained a hydrosol of ferric phosphate, Lottermoser and E. v. Meyer J colloidal silver halides, while Lotter-moser has made a whole series of hydrosols of difficultly soluble salts. Recently the number of these hydrosols has been greatly increased by the work of von Weimam. ... 

Coagulation of silver halide by hydrolyzed aluminum salts was shown by Matijevi6, Kratohvil, and Sticles (267) to be inhibited by fluoride ion which formed complex ions with aluminum. Similar reduction in coagulation effectiveness of other metal cations such as Fe and Th on colloidal silica may be anticipated. 

Double decomposition is the usual way of forming sols of insoluble salts Silver halides easily give colloidal solutions by mixing of silver nitrate and alkali halide solu-> tions. A sol of arsenic trisulphidc is obtained by introducing hydrogen sulphide into a saturated solution of arsenic trioxidc ... 

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