The aroma and commercial value of tea are due to a small quantity, (from 1/4 to 1 per cent.) of a volatile oil which it contains. This oil, as in coffee, is developed by roasting, the fresh picked leaves having neither an astringent, aromatic, nor bitter taste. But the effects of tea are due to its theine and tannin. Theine is present in all kinds of tea, as well as in coffee and cocoa, but it has no flavor. Tannin forms from a fifth to a seventh of the weight of the dried tea leaf, and is the more completely extracted the longer the tea is infused, or “draws.” Its precise effect upon the system is not fully known. Black tea contains less theine, essential oil, and tannin, than green tea. The Chinese pour hot water upon their tea, and drink it clear, and in Russia a squeeze of lemon takes the place of our cream. The Chinese sometimes flavor their fine teas with the cowslip colored blossoms of the sweet-scented olive and other odoriferous plants; and they also adulterate them with foreign or exhausted tea leaves, or with tea dust, called “Lie tea.” But good authorities declare that fair grades of tea are not now much or necessarily adulterated, and that the old idea that green teas are colored or faced with copper is erroneous; at least experts have not been able to detect even traces of it. Tea Made to Order. There are tea coloring and facing establishments in this country which use for the purpose substances very similar to those used by the Chinese, and they have become so expert of late years that they can turn a black tea into a green (or _vice versa_) at short notice. Tea buyers judge quality by the aroma, flavor, and the color and strength of the infusion. They detect vegetable adulterations by the shape and size of the leaf when unrolled, and sometimes burn the leaves and weigh the residue of ash. Gunpowder, Hyson, and Imperial. Some of the most experienced tea dealers in New York declare that there is really no essential difference in the quality of the “Firsts” or choicest grades of any “Chop” of either Gunpowder, Hyson, or Imperial, the only difference being in the form or fineness of granulation. But the popular preference in green tea is for Gunpowder, which is believed to consist of the first leaves or leaf buds of the plant. It is graded from “common” or “fair” up to “choicest.” Varieties of Tea.