Colloidal cobalt arsenate

Colloidal cobalt arsenate has been obtained in the form of an opalescent jelly either by mixing in the cold a solution of a cobalt salt of a strong acid with potassium dihydrogen orthoarsenate,8 or by successively treating an aqueous solution of a cobaltous salt with ammonium sulphate, acetic acid and an excess of sodium orthoarsenate.9... 

Colloidal manganese arsenate may be obtained in an analogous way to that described for cadmium and cobalt arsenates.7 If concentrated solutions of manganous chloride and potassium dihydrogen arsenate are mixed at the ordinary temperature, a solid jelly is formed, which remains stable for weeks but finally, rose-coloured crystals separate and the jelly partly liquefies.8 The essential constituent of the jelly appears to be the monohydrogen arsenate, MnHAs04, and the crystals are the monohydrate, MnHAs04.Ha0. 

Duran, J.D.G. Gonzallez-Caballero, E. (2000) Stability of cobalt-ferrite colloidal particles. Effect of pH and applied magnetic field. Langmuir 16 7954-7961 De Vitre, R. Belzile, N. Tessier, A. (1991) Spe-ciation and adsorption of arsenic on diage-netic iron oxyhydroxides. Limnol. Oceanogr. 36 1480-1485... 

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