Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/64

56 pigment, being but little affected by exposure to light and air.

Manganese brown is an oxide of manganese, of a fine, deep, semi-opaque brown, of a good body, and dries well in oil. It is artificially prepared from the waste still-liquors of the chlorine manufacturer by precipitating the liquors with sodium carbonate, collecting the precipitate and calcining in a furnace to a low red heat, until samples taken out and allowed to cool show the desired shade. It is a good and permanent pigment, but it is difficult to use on account of its excessively strong drying properties.

Greens. These, of course, may be made by mixing blue and yellow together, but such mixtures are less durable than those produced direct from copper, arsenic, etc. The latter are, however, objectionable for use in distemper or on wall papers, as they are very injurious to health. Brunswick green of the best kind is made by treating copper with salammoniac. Chalk, lead and alum are sometimes added. It has rather a bluish tinge, dries well in oil, is durable, and not poisonous. Common Brunswick green is made by mixing chromate of lead and Prussian blue with sulphate of baryta. It is not as durable as real Brunswick green. Mineral green is made from bi-basic carbonate of copper; it weathers well. Verdigris is acetate of copper. It furnishes a bluish-green color, durable in oil or varnish, but not in water; it dries rapidly, but requires great care in using owing to its poisonous qualities. Green verditer is a carbonate of copper and lime; is not veiy durable. Prussian green is made by mixing different substances with Prussian blue. There are a number of other greens made from copper, but they all possess in a greater or less degree the same qualities as the foregoing. Emerald or Paris green is made of verdigris mixed with a solution of arsenious acid. It is of a very brilliant color, but is very poisonous; is difficult to grind, and dries badly in oil. It should be purchased ready ground in oil, as in that case