MAGNESITE.--The mineral known by this name is a natural carbonate of magnesia, just as limestone is a natural carbonate of lime. Where sufficiently abundant it is quarried, ground, and levigated much in the same manner as barytes, which it greatly resembles in its qualities as a pigment, and for which it constitutes a suitable substitute. It is very white, heavy, and opaque; permanent in ordinary situations; neutral with other pigments, mixes equally well with oil or water, and possesses good covering power. MINERAL WHITE.--One of the names applied to the pigment prepared from gypsum, see p. 183. ORR’S ENAMEL WHITE.--A name derived from the maker of a certain variety of the zinc sulphide pigments, described under zinc whites, p. 254. PARIS WHITE.--Another name for the best brands of whiting, see below. PERMANENT WHITE.--This name is often bestowed upon baryta white (see p. 170), on account of its durability as compared with white lead. SATIN WHITE.--There is a certain amount of confusion in the application of this term, for while it is sometimes referred to baryta white (p. 170), it is also a synonym for fine gypsum (see p. 183). SPANISH WHITE.--The most carefully prepared samples of whiting (see below), are often known by this name. STRONTIA WHITE.--Though much less common than the closely similar sulphate of barium, the natural sulphate of strontium is equally suitable for employment as a pigment, and is prepared in exactly the same way as baryta white (see p. 170). The artificial product is also used. Both possess qualities remarkably akin to those of baryta white. TERRA ALBA.--An old-fashioned name for levigated gypsum (see p. 183). WHITING.--This material is simply prepared chalk. It should be soluble in hydrochloric acid with effervescence, leaving at the most but a small residue. Sometimes samples of whiting are found which are more or less alkaline or caustic in their properties. This is a serious defect for many purposes. It can be detected by treating the sample with water, and adding to the liquor a little phenolphthalein. If a brilliant red colour is obtained, caustic lime is present, and the sample should be rejected, if to be used for mixing with chromes or Brunswick greens, where a neutral product is required. Chalk itself is too familiar to need any description beyond saying that it essentially consists of carbonate of lime, with always a small percentage of silica associated with it.