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Chromate of Potassa

The of a dark-purple color, inodorous, and of a yellow chromate of potash of commerce is sweetish, astringent taste. It is a powerful only prepared on the large scale from the disinfectant, and oxidizing agent, from the crude chrome ore, and is the common source facility with which it parts with its oxygen. cf nearly all the other compounds of chromium. It has been found useful in medicine in various The ore, freed as much as possible from its im- ways, and forms an excellent, though unstable purities, is ground to powder in a mill, and hair dye. (See No. 1211.) It may be obmixed with or of its weight of bruised tained by mixing 8 parts of peroxide of nitre, and in this state exposed to a powerful manganese with 7 parts chlorate of potassa, hoat for several hours, on the hearth of a both in fine powder, adding 10 parts of hydrate reverberatory furnace, during which time it is of potassa, dissolved in a small quantity of frequently stirred up with iron rods. The water, evaporating to dryness, powdering, calcined matter is next raked out and lixi- exposing the powder to a low red heat in viated with hot water. A beautiful yellow- a plantinum crucible, dissolving the mass in a colored solution results, which is evaporated large quantity of water, decanting, evaporabriskly over a naked fire, when the chromate ting, and crystallizing. These crystals are percf potash falls down under the form of a gran- manganate of potassa. The PERMANGANATES ular yellow salt, which is removed from time or basic compounds of permanganic (mangato time with a ladle, and thrown into a wooden nesic) acid are all marked by their rapid vessel, furnished with a bottom full of holes, decomposition when in contact with organic called the draining-box, where it is left to matter. (Cooley.) 4191. Tests for Permanganate of boiling it in water, and crystallizing; it is Potassa. A very dilute solution has a then again dissolved in boiling water, and rose-color, free from green tinge, and is in- decolorized with charcoal (see No. 1729), and stantly decolorized by arsenite of potassa, aluminous clay; the resulting clear liquid is with the formation of a brown precipitate. allowed to cool slowly, forming crystals of (U. S. Ph.) Dissolve 44 grains granulated the cream of tartar of commerce. sulphate of iron in 2 fluid drachms dilute 4198. Bromide of Potassium. Put 1 sulphuric acid; the solution should completely troy ounce iron filings into 1½ pints distilled decolorize 5 grains of the permanganate dis- water; add 2 troy ounces bromine, stirring solved in water. (Br. Ph.) frequently during 30 minutes; heat gently