This pigment is also made by heating 14 parts of manganic oxide, 80 parts of barium nitrate and 6 parts of barytes with access of air until the desired shade appears. The mass is then ground in a continuous current of water until it is changed into a very fine powder and nothing more is dissolved by the water. The best result is obtained by Rosenstiehl’s process: 4 parts of barium hydrate, 2 parts of finely-powdered barium nitrate and 0·5 part of artificial manganese dioxide are rapidly mixed; the mixture is moistened and heated to a dark red heat. The fused mass is boiled out with water and the residue dried under a bell jar, under which are dishes of sulphuric acid and caustic potash, the former of which absorbs the water, whilst the latter keeps the air free from carbonic acid, which would injure the shade of the moist substance. Manganese green is amongst the pigments more recently discovered. On account of its high price it has found but limited use up to the present. It may be used in any vehicle, and is distinguished by great permanence. In regard to the preparation of this colour by Rosenstiehl’s method, which of all gives the best results, it should be observed that the shade largely depends on the quantity of barium hydrate used; the greater this is the more the shade inclines to blue. If it is desired to produce a colour of a greener tone than is produced by the fusion, this can be accomplished by boiling for a very long time with very weak hydrochloric acid, which extracts a portion of the base from the compound and produces a deeper shade. =Böttger’s Barium Green.=—A beautiful green is obtained by the process given by Böttger, as the author has found. It consists of barium manganate. The process is, however, somewhat costly, so that the pigment would only be available for artists’ purposes. A solution of potassium manganate is first made by gradually adding 2 parts of very pure pyrolusite, finely powdered, to a fused mixture of 2 parts of caustic potash and 1 part of potassium chlorate, bringing the mass to a low red heat after the introduction of the whole of the pyrolusite, and finally extracting with water, in which the potassium manganate dissolves to a fine emerald green solution. This process is unattended by difficulty if the pyrolusite contains a sufficient quantity of manganese peroxide and is in a sufficiently fine powder, which is most important. Potassium manganate is a very unstable substance. Cold water must be used to dissolve it, and the solution should not long stand exposed to the air, but should at once be used to obtain barium manganate.