472 TERNSTREMIACEZ OR CAMELLIACEA. 
Gordonia.--The bark is astringent, and is therefore useful in tanning, 
for which purpose it is sometimes employed in the United States. 
Kielmeyera speciosa.—The leaves of this plant, which is a native of Brazil, 
contain much mucilage, and are used on that account for fomentations. 
Thea or Camellia.—The genus Thea is now more generally regarded as 
not really distinct from that of Camellia, and hence the species of the two 
genera are frequently included under one genus, which is named by botanists 
either Camellia or Thea. Formerly it was supposed that China Tea, which 
is so extensively used as a beverage in this and many other countries, was 
prepared from the leaves of three species, two being natives of China, namely, 
Thea Bohea and T. viridis ; and another, a native of Assam, Thea assamica. 
Nearly all botanists are, however, now agreed that these three supposed 
species are only varieties of one, which is termed Thea chinensis or Camellia 
Thea. It was also formerly supposed that Black and Green Teas were the 
produce of distinct plants ; but Fortune, Ball, and others have proved that 
both Black and Green Teas may be made indifferently from the same plant, 
the differences between such teas depending essentially upon their mode of 
preparation. Thus, Green Teas are prepared by drying the leaves as quickly 
as possible after they are gathered; and then slightly heating them ; after 
which they are rolled separately or in small heaps, and then dried as quickly 
as possible ; while Black Teas are made from the leaves, which, after being 
gathered, are exposed to the air for some time, and then, after having been 
tossed about, are placed in heaps, where they undergo a kind of fermentation ; 
after which they are exposed to a fire for a short time; then rolled in masses 
to get rid of the moisture and to give them a twisted character ; then they 
are again exposed to the air, and subsequently exposed for a second time in 
a shallow pan to the heat of a charcoal fire, rolled again, and exposed to the 
air, and finally dried slowly over a fire. Thus, Green Tea consists of the 
leaves quickly dried after gathering, so that their colour and other proper- 
ties are in a great measure preserved ; while Black Tea is composed of 
the leaves dried some time after being gathered, and after they have 
undergone a kind of fermentation, by which their original green colour is 
changed to black, and other important changes produced. A great part 
of the Green Tea which is exported from China, and consumed in this 
country, and in other parts of Europe and America, is coloured artificially 
with a mixture of prussian blue, turmeric, and gypsum, Several varieties 
of Black and Green Teas are known in commerce. Thus of the former we 
have Bohea, Congou, Souchong, Pekoe, Caper, &c.; of the latter, Hyson, 
Hyson-Skin, Twankay, Gunpowder, &c. Some teas have a particular odour 
somewhat resembling the flowers of the common Cowslip; this is produced 
by mixing with them the dried flowers of the sweet-scented Olive ( Olea 
fragrans). Other teas are scented with the dried flowers of Chloranthus 
inconspicuus, Aglaia odorata, &c. 
The cultivation of the ‘Tea-plant is now being carried on with great 
success in India. Thus, in 1882 no less than 60,000,000 lbs. of Tea were ex- 
ported, and its cultivation is largely increasing. A large quantity of Tea 
is also at the present time produced in Japan and Java. China, however, is 
the great tea-producing country: in that part of the world,nearly 4,000,000 
acres of ground are devoted to it alone,and the total annual produce, at the 
present time, is probably not less than 600 millions of pounds. In the United 
Kingdom, the consumption of Tea has very much increased of late years. 
Thus, in 1840, it was only 50,000,000 lbs., while at the present time it amounts 
to about 140,000,000 lbs. Tea owes its chief properties to the presence of a 
volatile oil, tannic acid, and more especially the alkaloid, called theme, 
Theine is identical with caffeine, the alkaloid contained in Coffee, and is official 
under that name in the British Pharmacopeeia, and guaranine the alkaloid 
of Guarana, and is closely allied to theobsomine the alkaloid of cocoa-seeds. 
(See Coffea, Paullinia, and Theobroma.) Tea-leaves also contain about 
