Arsenious acid Colloidal

Both positively and negatively charged colloids have been prepared. The former results when the hydrated oxide is pejotised with chromic chloride, or may be formed by hydrolysis of the chloride or nitrate the latter is prepared by peptising the hydrous oxide with sodium or potassium hydroxide, or by adding sodium hydroxide to chromium nitrate solution in presence of arsenious acid and then dialysing. ... 

The Adsorption of Arsenious Acid. — Biltz has studied the adsorption combination of arsenious acid with colloidal iron oxide. The complex was previously given a definite chemical formula and was regarded by Bunsen, who discovered that the hydrogel of iron was an... 

Stable hydrosols may be obtained similarly by reduction of arsenious oxide, dissolved in aqueous sodium hydroxide containing some other protective colloid such as gelatin or egg-albumin, by means of alkaline pyrogallol.6 Salts of metallic acids, such as sodium antimonate or calcium plumbate,-with or without the addition of protalbic acid, may also be employed as protective colloids.1... 

Colloidal saccharated iron is sometimes used in place of ferric hydroxide as an antidote in arsenical poisoning, but its adsorptive capacity depends on the alkalinity of the medium.4 Thus a commercial preparation containing 0-75 per cent, of sodium hydroxide was found to adsorb 12-57 per cent, of arsenious oxide (reckoned on the amount of iron present) addition of alkali increased the adsorption until, with 1-28 per cent, of sodium hydroxide present, there was a maximum adsorption of 27 per cent. The addition of acid correspondingly diminished the adsorption. A gel of ferric magnesium hydroxide, if prepared without boiling, also adsorbs arsenic from sodium arsenite solutions.5... 

Mercury Derivatives.—The mode of preparation of these compounds is similar to that adopted for the preceding compounds. When mercuric chloride is used and the operations are carried out in methyl alcohol, a yellow powder results, which is soluble in methyl alcohol, glycerine, ethylene glycol, and acidified potassium iodide solution. It is decomposed by water or sodiunr hydroxide aird is only slightly soluble in dilute acids, but if treated with antimony compounds, antimonyl derivatives are obtained, which are more soluble and are stable in alkaline solutions. The decomposition by water is said to give rise to colloidal mercury and 3-amino-4-hydroxyplienylarsenoxide, OH.CgHa.(NH2).AsO. If an excess of mercuric chloride is used, the oxidation proceeds to o-aminophenol, mercurous chloride, and arsenious... 

In the case of arsenious sulfide sulfoarsenious acid may be formed and the anion adsorbed by the particles. At present it is difficult to determine which of these points of view is the correct one. In any event the negative charge is occasioned by adsorption of ions, or by ionization on the surface of the particles. The colloidal chemistry of the future will undoubtedly have to deal with the adsorption of ions by ultramicrons. 

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