=Chinese Green, Lokao.=—Under this description a green lake has recently been imported from China. It is a valuable pigment. Chinese green is sold in flat cakes, which are blue, with a green or violet lustre. The powdered lake is pure green and partially soluble in water; it contains colouring matter, water and inorganic matter consisting chiefly of clay and lime. Chinese green is made in China in a peculiar manner from the twigs of certain species of _Rhamnus_. According to report, the bark is boiled with water and a cotton cloth immersed in the decoction. The fibre fixes a colourless substance which becomes green on exposure to air. The cotton is repeatedly dipped into the decoction until it has absorbed a large quantity of colouring matter. It is then washed with cold water and boiled with water upon which cotton yarn is laid. The colouring matter suspended in the liquid adheres to the yarn, which is washed with a little cold water, and the colouring matter then collected upon paper and dried. If Chinese green is really made by this process, it is not a lake but a vegetable colouring matter, to which clay has been added to increase its weight or to make it plastic. Very fine lakes can be obtained from Chinese green by dissolving it in a solution of alum, and adding soda solution. When Chinese green is dissolved in acetic acid and ammonium chloride and a zinc salt added, a blue lake is produced on the further addition of sodium acetate. A bluish violet lake is obtained by treating Chinese green with a strong reducing agent and adding calcium acetate. =Charvin’s Green.=—The very high price at which genuine Chinese green was sold whilst it was still a novelty, gave rise to attempts at imitation. Charvin, of Lyons, succeeded in producing a pigment from _Rhamnus_ which has the characteristic property of Chinese green of retaining its colour in artificial light. He plunged the bark of common buckthorn into boiling water, boiled for a few minutes, and allowed the whole to stand for twenty-four hours. Lime water was added to the brown liquid, which was then exposed to the action of the air in shallow vessels, when it gradually turned green and deposited a green precipitate. When this appeared, the liquid was brought into glass vessels and potassium carbonate solution added so long as a precipitate resulted, which after drying had all the properties of genuine Chinese green. Although for some time Chinese green was a very fashionable colour, its use is now almost discontinued, although it can be used with advantage as an artists’ pigment, and its preparation by Charvin’s method is neither difficult nor specially costly. CHAPTER LXIV. BROWN ORGANIC PIGMENTS.