Colloidal arsenious oxide

Colloidal arsenious oxide may be obtained in a highly dispersed condition by the vaporisation of arsenic in the electric arc and oxidation of the fume in a current of air.11 The size of the particles thus obtainable corresponds with the upper limit of the colloidal state (100 ftp.). 

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 arsenic is also formed by electrolytic reduction of a cold alkaline solution of arsenious oxide using a platinum cathode and a mercury anode,8 a small current density being employed a trace of... 

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... 

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... 

Colloidal solutions may also be made by dispersing in the solvent j a solid or liquid substance which is normally insoluble, such as gold, ferric oxide, arsenious sulfide, etc. A colloidal solution of this sort consists of very small particles of the dispersed substance, so small that their temperature motion (Brownian movement) prevents them from settling out in the gravitational field of the earth. 

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. ... 

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... 

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