CHAMELEON MINERAL. A com pound of manganesic acid and potash, which presents a variety of tints when dissolved in water. As it has of late been largely employed for whitening tal palm oil, and decoloring other or game matters, it merits description. It exists in two states ; one of which is called by chemists the manganate of pot ash, and the other the oxymanganate ; denoting that the first is a compound of manganic acid with potash, and that the second is a compound of oxymanganic acid with the same base. They are both prepared in nearly the same way • the former by calcining together, at a red heat in a covered crucible, a mixture of one part of the black peroxide of manganese with three parts of the hydrate of potash (the fused potash of the apothecary). The mass is of a green color when cold. It is to be dissolved in cold water, and the solution allowed to settle, and become clear, but by no means filtered for fear of the decomposition to which it is very prone. When the decanted liquid is evaporated under the exhausted receiver of an air pump, over a surface of sul phuric acid, it affords crystals of a beau tiful green color, which should be laid on a clean porous brick to drain and dry. They may be preserved in dry air,. but should be kept in a well-corked bottle. They are decomposed by water, but dis solve in weak water of potash. On dilut ing this much, decomposition of the salt ensues, with all the chameleon changes of tint ; red, blue, and violet. Sometimes a green solution of this salt becomes red on being heated, and preserves this co lor even when cold, but resumes its green hue the moment it is shaken. The ori
ginal calcined mass, in being dissolved, always deposits a considerable quantity of a brown powder, which is a compound of the acid and peroxide of manganese com bined with water. Much of the potash remains unchanged, which may be reco vered.
A permanent oxymanganic salt may he made as follows :—Melt chlorate of pot ash over a spirit lamp, and throw into it a few pieces of hydrate of potash, which immediately dissolve, and form a limpid liquid. When peroxide of manganese in fine powder is gradually introduced into that melted mixture, it immediately dis solves, with the production of a rich green color. After adding the manganese in excess, the whole is to be exposed to a gentle red heat, in order to decompose the residuary chlorate of potash. It is now a mixture of manganate of potash, chloride of potassium and peroxide of manganese. It forms with water a deep green-colored solution, which when boiled assumes a fine red color, in conse quence of its becoming an oxymanganate, and it ought to be decanted off the sedi ment while hot. By cooling, and still more after further evaporation, the oxy manganate of potash separates in crystals possessed of great lustre ; but toward the end colorless crystals of chloride of potas sium.