If the analysis of the tea-ash is referred to it will be noted that more than one-half of it should be soluble in water, so that for all practical purposes a complete analysis is not requisite, a determination of the ratio of _soluble_ to _insoluble_ parts of the ash being sufficient. Such a determination is made by boiling the ash several times with a little water, filtering and washing the residue in the filter, drying the precipitate, igniting and weighing it. The weight of the insoluble part of the ash may then be subtracted from the weight of the entire ash, in which manner both the percentage of the soluble and insoluble ash will be conveniently arrived at, in which case the following determination of the percentage of “soluble” and “insoluble ash” in 100 parts of spurious leaves and pure tea when completely dried will be of interest here:— Kind of Leaf. Soluble Ash. Insoluble Ash. Ash, 3.19 7.48 Plum, 5.66 4.24 Willow, 4.16 5.18 Teas of commerce, 3.55 2.47 Proving that in spurious leaves the ratio of soluble or insoluble ash is very different from what it is in genuine tea-leaves, and that an ash of such composition cannot be very soluble in water. Peligot has also pointed out that tea leaves differ from other leaves by their extraordinary richness in nitrogen, the prepared leaf being by the process of curing rendered still more nitrogenous than the raw or spent leaves, the former averaging, according to his experiments, 6 per cent. of nitrogenous matter, and the latter 4.37, so that if the tea-leaf be unique in containing such a high percentage of nitrogen, it is obvious that a determination of nitrogen in tea may also be useful as a method of identification. The tea-extract also yields a comparatively large quantity of ammonia when it is boiled with potash or permanganate of potash, and it is probable that this characteristic may also prove very valuable in the testing of tea. A solution containing about 10 per cent. of solid potash, free from ammonia and nitrogenous matter is required for the purpose, and easily obtained. So that a deficiency of theine, a deficiency of nitrogen, and a deficiency of ammonia are all indicative of the presence of foreign leaves in tea. SPENT OR EXHAUSTED LEAVES IN TEA