_b. Ash insoluble in water._--The total ash obtained in _a_ is washed into a beaker and boiled with water for a considerable time. It is then brought upon a filter and the insoluble residue washed, dried, ignited, and weighed. In unadulterated tea it will not exceed 3% of the sample taken. _c. Ash soluble in water._--This proportion is obtained by deducting ash insoluble in water from the total ash. Genuine tea contains from 3% to 3.5% of soluble ash, or at least 50% of the total ash, whereas in spent or exhausted tea the amount is often but 0.5%. _d. Ash insoluble in acid._--The ash insoluble in water is boiled with dilute hydrochloric acid and the residue separated by filtration, washed, ignited, and weighed. In pure tea the remaining ash ranges between 0.3% and 0.8%; in "faced" teas, or in teas adulterated by the addition of sand, etc., it may reach the proportion of 2% to 5%. Fragments of silica and brick-dust are occasionally to be found in the ash insoluble in acid. THE EXTRACT.--Two grammes of the carefully-sampled tea are boiled with water until all soluble matter is dissolved, water being added from time to time to prevent the solution becoming too concentrated. The solution is poured upon a tared filter, and the remaining insoluble leaf repeatedly washed with hot water until the filtered liquid becomes colorless. The filtrate is now diluted to a volume of 200 c.c., and of this 50 c.c. are taken and evaporated in a weighed dish over the steam-bath until the weight of the extract remains constant; its weight is then determined. Genuine tea affords from 32% to 50% of extract, according to its age and quality; in spent tea the proportion of extract will be greatly reduced. INSOLUBLE LEAF.--The insoluble leaf obtained in the preceding operation, together with the weighed filter, is placed in an air-bath and dried for at least eight hours at a temperature of 110° C.; its weight is then determined. In unadulterated tea the amount of insoluble leaf ranges between 47% and 54%; in exhausted tea it may reach a proportion of 75%. It should be noted that in the foregoing estimations the tea is taken in its ordinary air-dried condition. If it be desired to reduce the results obtained to a dry basis, an allowance for the moisture present in the sample (an average of 8%), or a direct determination of the same, must be made. The following tabulation gives the constituents of genuine tea so far as the ash, extract, and insoluble leaf are involved: _Total ash_--ranges between 4.7% and 6.2%. _Ash soluble in water_--ranges between 3% and 3.5%; should equal 50% of total ash. _Ash insoluble in water_--not over 2.75%. _Ash insoluble in acid_--ranges between 0.3% and 0.8%. _Extract_--ranges between 32% and 48%. _Insoluble leaf_--ranges between 43% and 58%.