BARYTA GREEN.--It is said that the manganate of baryta makes an excellent green pigment, which may with advantage replace for many purposes those greens which contain arsenic. Several methods of preparing it have been published:--(_a_) One consists in igniting together the nitrate of baryta and manganese oxide or dioxide. (_b_) Another consists in fusing a mixture of pyrolusite or black oxide of manganese, caustic bartya, and chlorate of potash. (_c_) According to a third method, mix 2 parts caustic soda and 1 part chlorate of potash, and gradually add 2 parts very finely powdered manganese; heat gradually up to dull redness, then allow to cool, powder, and exhaust with water; filter and cool, and add a solution of nitrate of baryta to the filtrate; a violet-coloured baryta precipitate forms; this is carefully washed, dried, and treated with ½-1 part of caustic baryta, hydrated, and gradually heated up to redness, with constant stirring. The cooled mass is powdered, and finally washed to remove any excess of baryta. By either process a green mass is obtained, but the second method seems to yield a more beautiful and homogeneous product. In experimenting with other and more direct methods for preparing a baryta green of great purity and beauty, Fleicher has made several observations of its properties. If a green solution of manganate of potash be precipitated, while boiling, by chloride of barium, a heavy, granular, but not crystalline, precipitate of manganate of barium is obtained. This precipitate has a violet colour, approaching blue, can be washed by decantation at first, and afterwards may be collected on a filter. On drying the precipitate, its colour grows lighter with the increase of temperature; and on being heated to a dark red heat, it looks almost perfectly white, with only a shade of greyish blue. If, then, it be heated still higher with free access of air, or in an oxidising flame, it gradually turns green; by carrying the process farther the colour becomes a beautiful greenish-blue, and finally, at a very high heat, a dirty greyish-brown mass is formed from the reduction of the manganic acid to binoxide of manganese. On adding chloride of barium to a solution of the permanganate of potash, and boiling, a precipitate is slowly formed of a peach-blossom colour, while the liquid retains a deep violet colour. By decanting and bringing the mass, diluted with water, on a filter, the precipitate is not decomposed, and can be dried at 212° F. without changing colour. When the dry permanganate of barium is gradually heated, its colour also grows paler, but does not, like the manganate of baryta, acquire a green colour at a still higher temperature; for after the colour has once vanished, an increase of temperature soon converts it into the greyish-brown mixture of the binoxide of manganese and baryta or carbonate of baryta. Hence it is impossible to prepare the green manganate of baryta from the permanganate.