rom two to three feet,
much in the same manner as the vine is treated in France. They pluck the
leaves, one selecting them according to the kinds of tea required; and,
notwithstanding the tediousness of the operation, each labourer is able
to gather from four to ten or fifteen pounds a day. When the trees
attain to six or seven years of age, the produce becomes so inferior
that they are removed to make room for a fresh succession, or they are
cut down to allow of numerous young shoots. Teas of the finest flavour
consist of the youngest leaves; and as these are gathered at four
different periods of the year, the younger the leaves the higher
flavoured the tea, and the scarcer, and consequently the dearer, the
article.

1795. The various names by which teas are sold in the British market are
corruptions of Chinese words. There are about a dozen different kinds;
but the principal are Bohea, Congou, and Souchong, and signify,
respectively, inferior, middling, and superior. Teas are often perfumed
and flavoured with the leaves of different kinds of plants grown on
purpose. Different tea-farms in China produce teas of various qualities,
raised by skilful cultivation on various soils.

1796. Tea, when chemically analyzed, is found to contain woody fibre,
mucilage, a considerable quantity of the astringent principle, or
tannin, a narcotic principle, which is, perhaps, connected with a
peculiar aroma. The tannin is shown by its striking a black colour with
sulphate of iron, and is the cause of the dark stain which is always
formed when tea is spilt upon buff-coloured cottons dyed with iron. A
constituent called _Theine_ has also been discovered in tea, supposed to
be identical with _Caffeine_, one of the constituents of coffee. Liebig
says, "Theine yields, in certain processes of decomposition, a series of
most remarkable products, which have much analogy with those derived
from uric acid in similar circumstances. The infusion of tea differs
from that of coffee, by containing iron and manganese. We have in tea,
of many kinds, a beverage which contains the active constituents of the
most powerful mineral springs, and, however small the amount of iron may
be which we daily take in this form, it cannot be destitute of influence
on the vital processes."

1797. Chinese tea has frequently been adulterated in this country, by
the admixture of the dried leaves of certain plants. The leaves of the
sloe, white thorn, ash, elder, and so