Theine is extracted from tea by boiling a quantity of the leaves in a considerably larger quantity of distilled water and the liquor squeezed out of the leaves which are to be boiled with a fresh quantity of water and again subjected to pressure, the process being repeated a third time. The several portions of the infusion expressed from the leaves are put in the same vessel, mixed together thoroughly and treated with an excess of acetate of lead and ammonia, which precipitates the tannin and coloring matter. The liquor is next filtered and the filtrate evaporated down to a small bulk, first over a naked flame and afterwards in a water bath, and on being allowed to cool the solution will deposit crude theine which is removed by filtration, and the filtration nearly dried up in the water bath, and the residue boiled with alcohol, which dissolves the theine out of it. From this hot alcoholic solution theine crystallizes on cooling, a final purification being effected by crystallization from ether and decolorizing with animal charcoal. A simpler but less effective method is to place the dust of finely powdered tea-leaves, or an evaporated watery extract on a watch glass and cover it with a paper cone and hold it over a spirit lamp or gas jet the vapor arising from the glass condenses on the interior of the cone and forms small crystals of theine. Concentrated sulphuric acid dissolves theine in the cold without the production of color, but if the alkaloid be treated with nitric acid evaporated to dryness, and the reddish-yellow residue moistened with a little ammonia it turns a splendid purple color. Again, if a solution of theine be evaporated with chlorine on a watch glass a reddish-brown residue is obtained, which if again treated with the vapor of ammonia it becomes a deep violet of which the chief precipitants will be phosphoric acid, iodine and platinum, forming a yellow and brown precipitate respectively. Theine having no odor and only a slightly bitter taste it obviously has very little to do with the flavor of tea. It is, however, considered a very valuable constituent on account of the large percentage of nitrogen which it contains and to which is attributed the peculiar physiological action of tea on the animal economy, but what changes it undergoes in the human system has not yet been determined. When oxydized artificially it decomposes into methleamic (hydrocyanic) acid, a nitrogenous compound closely allied to caseine or gluten, and as hot water extracts but very little of this substance a large amount of it is wasted in the ordinary infusion, which might otherwise be saved by the addition of a little carbonate of soda to the water in preparing it.