(1) When the tea is heavily coated it may be easily recognized by its dull leaden-blue color and greasy appearance in the hand, or by placing a small quantity of the leaves on a piece of glass or smooth table, on removing them the coloring-matter will be found adhering to the hands, glass or table, and its nature, whether Prussian blue, turmeric, kaolin or indigo, readily determined with the aid of a microscope. (2) When only lightly colored or suspected, place a sample of the leaves in a cup or wine-glass and pour on briskly boiling water and stir well for two or three minutes, then strain well through a thin muslin cloth. The coloring-matter, if any, will be found adhering to the cloth, that passing through, sticking to the sides, or forming a sediment at the bottom of the vessel into which it is strained. If these deposits be treated with a preparation of chlorine, or a solution of chloride of lime, and turn white, the coloring substance used is indigo. But if treated with a little potash, and it becomes brown, it will prove to be Prussian blue, the application of a little sulphuric acid having the effect of turning it blue again. What are known to trade as “Canton Green teas” are made from tea-dust and exhausted leaves ground up fine and aglutinized with a preparation of gum, glue or other starchy substance to unite and hold them together and then artificially colored or glazed. This fabrication is readily detected by crushing the so-called leaves between the fingers or rubbing them between the hands, upon which they leave a yellowish-brown stain, greasy in nature. Or by powdering a small quantity of the alleged leaves and treating the dust with a dilution of sulphuric acid it becomes very much discolored, and if it assumes a leaden-blue color on the application of caustic potash it is colored with Prussian blue. Again, place a small quantity of the leaves in a cup or glass and pour on boiling water, they will immediately begin to disintegrate and form a thick, gluey deposit at the bottom of the vessel. By treating this precipitate with a little iodine the mass will become separated and dissolve into its original dust. FOREIGN OR SPURIOUS LEAVES IN TEA.