BLACK PIG31 ENTs form a numerous class of bodies, though those in common use are easily enumerated. They appear in commerce principally under these names : - vegetable black, carbonized vegetable matter ; lamp black, soot of oils and fats ; Indian ink, preparation of lamp black ; ivory black, carbonized ivory and bone ; bone black, carbonized bone ; blue black, washed wood charcoal ; charcoal black, carbonized wood ; black wad, a native oxide of manganese ; black lead, a form of carbon ; tar, from distillation of organic substances.
Most of these blacks owe their colour to carbon. From the charring of vegetable substances are prepared Charcoal Black, Blau Black, and Vegetable Black, but these take many names according as they are prepared from carbonized wood, twigs of the grape vine, peach and other fruit stones, cork, the lees of wine, &c. Bone and rory Blacks again are carbonized animal substances, principally bones, which when skilfully burned yield dense durable blacks. Lamp Black of the best quality is the soot deposited from the imperfect combustion of oils and fats, and the soots of resin and tar are also collected and used under this name. Indian RI: (see vol. xiii. p. 80) is a form under which lamp black of the finest quality occupies an important position among pigments. Of the other blacks Tar is the most important owing to its extensive use as a preservative and antiseptic coating.
Several pigments are prepared on account of special properties apart from the protective and decorative purposes for which ordinary paints are applied. Among such may be mentioned Balmain's luminous paint, a preparation in oil or water of certain of the phosphorescent sulphides. Objects coated with this material have the property of continuing to emit light in dark situations for some time after they have been exposed in daylight or to high artificial light. The luminous paint has been proposed for coating buoys, signals, public notice boards, clock and watch dials, playing balls, match boxes, &c., but it has not come into extensive use. Powdered asbestos has been introduced as a fire-proof paint for wood ; but all common paints applied as distemper colour are equally fire-proof in the sense that they themselves are incombustible, and when they coat wood thickly they offer great resistance to an incipient fire, and even retard combustion under very high heat. Numerous anti-fouliag compositions for the painting of ships' sides and bottoms and anti-corrosive, immoxidizable, damp-proof, and water-proof paints have been patented, some of which are in extensive use. (J. PA.)