(8) Equal quantities of flowers of sulphur and bichromate of potash are thoroughly mixed, and heated to redness in a crucible, producing a mixture of oxide of chromium with sulphide and sulphate of potash. The latter are dissolved out by washing repeatedly with hot water, leaving the chromium oxide as a finely comminuted dense powder of an intense green colour. (9) A modification of (8) consists in adding small successive quantities of flowers of sulphur to a boiling concentrated solution of potash bichromate. From this results a gelatinous oxide of chromium, which is washed with boiling water, dried, and calcined in a crucible at a red heat. (10) Hydrochloric acid decomposes bichromate of potash, forming a soluble chloride of potash which can be removed by washing, and a residue of chromium oxide, which is washed on a filter and dried. There remain for description two or three processes in which phosphoric acid plays a part, but the greens made by these methods do not possess the freshness of the others, and it is difficult to see what advantages can attend this modification. (11) According to Arnaudon, 149 parts of bichromate of potash are thoroughly incorporated with 128 parts of crystallised neutral phosphate of ammonia, and the mixture is heated in thin layers to a temperature between 338° and 356° F., which brings about intumescence, change of colour, and disengagement of water and ammonia; the heating is continued for half an hour, but must not be allowed to exceed 392° F. When the development of the green colour is complete, the product is washed with hot water to remove soluble salts, and the residue constitutes an impalpable powder of chromium oxide, forming a leaf-green pigment. (12) Dissolve 10 lb. of bichromate of potash and 18 lb. of phosphate of soda in boiling water, and add to the boiling mixture 10 lb. of thio-sulphate of soda solution and a little hydrochloric acid. A precipitate of phosphate of chromium is gradually thrown down as the boiling is maintained.