Thus far I have chiefly endeavoured to trace the effects of Tea as a part of our diet. In medicine it has at present but very little reputation amongst us. It is even scarcely ever recommended as a part of the furniture of a sick chamber; it is seldom mentioned even as a gentle diaphoretic: in cases, however, where it is necessary to dilute and relax, to promote the thinner secretions, it promises at least as much advantage as most other infusions. For, besides its other effects, it seems to contain something sedative in its composition (Sect.II.Exp.III. IV.), not altogether unlike an opiate. Like this class of medicines, it mitigates uneasiness, perhaps more than any other merely aqueous infusion: and, like very small doses of opium, it sometimes prevents rest, and gives a temporary flutter to the spirits.
Where, therefore, large quantities of the infusion must be taken, to produce or support a considerable diaphoresis, a decoction of Tea, or a strong infusion, may be administered with great propriety, particularly in inflammatory complaints; the sedative power of Tea, assisted by the diluting effects of warm water, generally producing a diaphoresis, without stimulating the system. The Chinese most commonly give it as a medicine in decoction, in a variety of diseases; but if the infusion weredrawn from a large proportion of fine Tea, and soon poured off, that the finest part may be procured, and drank warm, it would seem preferable as an attenuant and relaxant.
I have more than once given fine green Tea in substance with some diluting vehicle, and observed the same effects nearly as are produced from taking the infusion. Thirty grains of this kind of Tea powdered, taken three or four times at as many hours interval, generally relaxes the solids, diminishes heat and restlessness, and induces perspiration. Such a dose as produces a slight nausea, which this quantity usually does, more certainly induces a perspiration, and a mitigation of the symptoms accompanying inflammatory complaints. If this dose be doubled, the nausea and sickness will be increased, and a disagreeable sensation or load is felt for some time about the region of the stomach, which usually goes off with a laxative stool.