Founded on these observations an assay of the tea-extract may be made by the following simple process: Put ten grams of tea into a pint flask and pour on about two-thirds of distilled water accurately measured, a cork and bent tube is then adapted to the mouth of the flask and a connection made with a condenser. The contents of the flask are next heated and made to boil strongly. That having been done the boiling is stopped and the flask and condenser disconnected and the distillate poured back into the flask and the decoction of tea observed closely. If quite clear fifty grams are weighed out and evaporated to dryness in a water-bath and weighed till constant. If the decoction be not quite clear by this time it is to be filtered hot; the first small filtrate is best thrown away and the filtrate collected, weighed, and dried in the water-bath until the residual tea-extract becomes quite constant. Having performed the operation in the manner directed, the weight of the tea-extract actually weighed will be the weight of the extract yielded by one gram of the sample to be assayed. But in coming to a decision as to the genuineness of a sample of tea of which an analysis has been made by this method, it is of importance to remember that genuine tea is subject to considerable variation in composition. The quality and condition of the leaf at the time of gathering and the different treatments which it undergoes in the process of manufacture, or whether the tea is Black or Green, cause the composition to exhibit a wide range of variation. Taking the percentage of the extract as a basis from which to start, that in genuine tea being from 32 up to 50 per cent. in its ordinary commercial condition. Such being the case, it is obvious that a determination of the percentage of extract will not enable the expert or analyst to say whether the sample of tea be of a lower or higher grade of pure tea, or whether it is composed of a high grade of genuine tea and a portion of exhausted leaves. In a general way, however, this question is not of vital importance to the analyst, as a solution may be arrived at from a determination of the soluble ash, which would be found rather deficient on incineration. For although tea may be exceptionally rich in extract, and although there are difficulties in the way of deciding whether a given sample of tea consists of average quality or of fine tea mixed with spent tea, there are no such difficulties in recognizing the case of tea of average grade, mixed with a considerable quantity of exhausted leaves, as it is assumed in this formula that the soluble ash in genuine tea is 3.6 per cent. and that in spent tea only 0.3 per cent. But in using this formula it must be understood that the results are only rough approximations, judgment and discrimination being required to determine by it.