Scientific American 11, 27. 11. 1852
From experiments lately made by a French chemist, it appears that the Chinese possess a green vegetable dye, unknown to the rest of the world, which is used for dyeing calicoes, &c. The first essays were made with a sample of the material, but through the kindness of Mr. Forbes, the American Consul at Canton, a small quantity of the dye itself was transmitted to Europe for examination.
It is in thin scales, of a blue color resembling, somewhat, Java indigo, but of a finer texture, and, moreover differing from that dye in its composition and chemical properties. On making an infusion in water, with a very small piece of this substance, the water soon changed to a blue color that reflected a greenish hue; a strip of calico, with the mordants of iron and alum steeped in it, took a real dye; the parts covered with alum passing to a sea grean, more or less deep according to the strength of the mordant; those covered with alum and the oxide of iron to a dark sea green approaching an olive green, and those with oxide of iron alone to a dark olive green. The parts untouched by the mordants remained white. It is concluded, from these experiments that the Chinese possess a coloring matter (lac) with the appearance of indigo, which changes to a green color with mordants of alum and iron, and that this coloring matter contains no indigo, nor anything bearing analogy to it. The Chamber of Commerce of Paris have directed inquiries to be made concerning its origin and preparation.
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