Zinc white

This consists of zinc oxide in the form of a light, odourless, white powder. It may contain, as impurities, lead carbonate and sulphate and oxides of iron, cadmium and arsenic, and may be adulterated with chalk, barium sulphate and clay (kaolin). Besides the technical tests already described (see General Methods), the following tests and determinations are made. 

Qualitative Examination,—A portion of the substance is moistened with ammonium sulphide a blackish coloration indicates presence of lead or iron, and a yellow one, cadmium or arsenic. The presence of the latter is best shown by dissolving about 1 gram of the substance in a little concentrated hydrochloric acid and adding 5 c.c, of Bettendorf s reagent (see VoL I, p. 18) presence of arsenic is manifested by a brown coloration, followed by a black precipitate if arsenic is absent, no coloration will be observed even after an hour. 

Another portion of the substance is boiled with water and filtered, the 

The residue insoluble in water or a new portion of the substance is treated with dilute acetic acid, in which the zinc oxide should dissolve easily without evolution of gas. Effervescence indicates carbonates (white lead, chalk) if hydrogen sulphide is evolved, zinc sulphide (lithopone) may be present. Any residue insoluble in acetic acid may contain lead, barium or calcium sulphate or day, these being recognised as in white lead (q.v., paragraph i). Lastly, the acetic acid solution, when treated with caustic soda, should give a white precipitate quite soluble in excess of alkali and the alkaline solution should give a white precipitate with ammonium sulphide. 

Moisture.—5 grams of the substance are dried in an oven at ioo° to constant weight. 

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Zinc oxide or zinc white is used in paints, but more preferable, because of its better covering power, is lithopone (a mixture of zinc sulphide and barium sulphate). Both paints have the advantage over white lead that they do not blacken in air (due to hydrogen sulphide). Zinc dust and also zinc chromate are constituents of... 

Deck-weiss, n. zinc white, -weissfarbe, /. (Varnish) white enamel, -wort, n. code word. Cf. Deckname. -ziegel, m. cover tile coping brick. 

Schneewelss, n. snow white (zinc white), schneidbar, a. capable of being cut, sectile, scis-sile. 

Zinc Oxide (Flowers of Zinc, Zinc White, Zinc Bloom, Philosopher s Wool, Chinese White,... 

Slow addition of zinc white (a voluminous oxide containing much air) to cover the surface of linseed oil varnish caused generation of heat and ignition. Lithopone, a denser (air-free) grade of oxide did not cause heating. 

The zinc sulphate produced in this process can be turned more easily to commercial account than iron sulphate. If to the solution of the zinc sulphate resulting from the process sodium carbonate or sodium hydrogen carbonate is added, a precipitate of hydrated zinc basic carbonate or zinc carbonate is obtained, which on ignition in a furnace yidds zinc oxide (commercially known as zinc white ), water, and carbon dioxide. Zinc white has a commercial value as a basis or body In paints it has one great advantage over white lead, which is used for the same purpose, in that it is far less poisonous. This method of treatment of the residual... 

Chinese white chem A term used in the paint industry for zinc oxide and kaolin used as a white pigment. Also known as zinc white. chTn nez wTt chinic acid See quinic acid. kin ik as ad chinoldine See quinoidine. ki noT.den chinone See quinone. kin on ... 

Zinc oxide is an example of zinc(Il) combining with a —2 anion. (Zn + O —> ZnO). Zinc oxide is also added to paints as a pigment and mold inhibitor and is known as zinc white when it is used as an oil paint by artists. It is used for cosmetics (ointment to protect nose and bps from ultraviolet sunlight), as a seed treatment, and as a dietary supplement. 

Synonyms zinc white zincite flowers of zinc... 

What is the composition of zinc white and titanium white Which white paint has better properties—a better hiding ability and an unchanging colour—when exposed to the air for a long time Under what conditions is normal lead carbonate prepared (compare with magnesium carbonate) ... 

IttiCnAz s zinc-white process, 11t4 Silesian process, 1J58-1)69/ U00-H62. silicate of, liydratod, 1353. 

The some inventor combines the principle of the reverberatory furnace in the distillation of zinc for the purpose of making zinc-white. In this arrangement he so disposes the retorts that the frame from the coal fire circulates round them, end then passes into a chamber over the dome Inclosing the retort, where pipes may he laid for raising the temperature of the air which ts forced into the space surrounding the months of the retarts to oxidise the zinc vapors. The oxide so produced ts conducted to receiving chambers in a manner somewhat similar to the two methods already described,... 

Zinc-white Paint.—Like white lead, tho oxide of zinc requires to be mixed with an oily vehicle, to be applied in painting. As oxide of zinc does not readily form a saponaceous compound with fate or oils like oxide of lead the paint which is prepared with it and ordinary linseed ofl, does not dry or harden for a long time. This peculiarity was at first one of the principal... 

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