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Tea (Camellia thea) is a
small evergreen shrub cultivated to a height of 7 to 8 feet, but
growing wild up to 30 feet high, much branched. The bark is rough
& gray. Leaves are dark green, lanceolate or elliptical, on
short stalks, blunt at apex, base tapering, margins shortly
serrate, young leaves hairy, older leaves glabrous.
It was formerly supposed that black and green
tea were the produce of distinct plants, but they are both
prepared from the same plant.
Green tea is prepared by exposing the gathered
leaves to the air until superfluous moisture is eliminated, when
they are roasted over a brisk wood fire and continually stirred
until they become moist and flaccid; after this they pass to the
rolling table, and are rolled into balls and subjected to
pressure which twists them and gets rid of the moisture; they are
then shaken out on flat trays, again roasted over a slow and
steady charcoal fire, and kept in rapid motion for an hour to an
hour and a half, till they assume a dullish green color. After
this they are winnowed, screened, and graded into different
varieties.
With black tea, the gathered leaves are exposed
to the air for a longer period, then gathered up and tossed until
soft and flaccid, and after further exposure, roasted in an iron
pan for about five minutes. After rolling and pressing, they are
shaken out, exposed to the outer air for some hours, re-roasted
for three or four minutes, re-rolled, spread out in baskets and
exposed to the heat of a charcoal fire for five or six minutes
and then rolled for the third time and again heated, and finally
dried in baskets over charcoal fires, from which process they
become black in color. China is the great tea-producing country,
over four million acres of ground being devoted to its
cultivation. In India also it is a very important product.
Tea has the following known constituents:
caffeine (theine), tannin (10-20% gallotannic acid),
boheic acid, volatile oil, aqueous extract, protein wax, resin,
ash and theophylline.
Tea is considered a strong stimulant and
astringent. Tea exerts a decided influence over the nervous
system, generally evinced by a feeling of comfort and
exhilaration; it also causes unnatural wakefulness when taken in
quantity. Taken moderately by healthy individuals, it is
harmless, but in excessive quantities it will produce unpleasant
nervous and dyspeptic symptoms, the green variety being decidedly
the more injurious.
Tea is rarely used as a medicine, but, the
infusion is useful to relieve neuralgic headaches.
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