The value of tea commercially, depends principally upon the character and flavor of the infusion and also on the aroma imparted to it by the volatile oil, which is not generally estimated by chemists owing to the imperfect methods of obtaining it and the difficulty attending the operation. But commercially the value of a tea is based on the amount of “extract” it yields as well as on the quantity of theine and tannin contained therein. Tea-testers and experts on the other hand take no account of theine, which is almost tasteless, but which is at the same time physiologically the most important constituent of tea. And so far as total extract is concerned Congou teas are inferior in quantity to Oolongs, Greens and Japans, while the latter in turn yield a larger percentage of theine than either India or Ceylons, notwithstanding that it is claimed that they yield less. Yet it must be admitted that a deeper color is imparted to the infusion by India and Ceylon teas, and that they are also of greater strength than China and Japan teas, in fullness (not delicacy) of flavor, the former claim is not borne out by either analysis or testing. There is also no uniform relation existing between the chemical composition of teas and their commercial value, as the percentage of extract determined by a half-hour’s boiling of the leaves in 100 parts of distilled water bears in China and Japan teas particularly a more uniform relation to the price, although the total extract obtained by exhausting the leaf is very irregular. This result is also quite in accord with the fact that the finer and more valuable qualities of all teas are to be found only in the youngest and tenderest leaves, the decline from the finer to the lower grades in the amount of theine dissolved being also noteworthy as showing the power to yield nearly all their theine, the latter doing so only to a limited extent under the same treatment. But although these results show the difference in the drawing qualities of all the various kinds of tea, yet they are not sufficiently uniform to make such analysis the basis for calculating the price of tea. It is evident, however, that the volatile or essential oil—to which tea owes it flavor and aroma—plays a more important part than any of the other constituents in determining the commercial value of tea. Again, it must be noted the strength and flavor of the infusion is as much due to the character of the water used in drawing as to any other cause, the quantity of tannin extracted by soft water being greater than that obtained by the use of hard.