CAOUTCHOUCS OR INDIARUBBERS. 39 
confined to the tropical zone, though the families to which 
they belong are not. The caoutchoucs or guttas are con¬ 
tained in the latex in the form of minute globules in the 
watery fluid, and when exposed to the air or treated with 
various chemical compounds they coagulate or clot, finally 
forming a tough more or less elastic mass, the rubber or gutta 
of commerce. The latex-containing or laticiferous vessels are 
most commonly in the inner bark of the tree, near to the 
cambium, and when the tree is wounded the latex flows 
out. These substances have been known for a long time 
to the natives of the tropics, and within the last fifty years 
have become indispensable in the arts. Until lately the 
supply was entirely from wild trees, but of recent years 
their cultivation has been taken up in Ceylon and elsewhere, 
and now bids fair to become an important industry. 
imported into Europe and America in 
enormous quantity, more than 100,000,000 lb. being con¬ 
sumed annually. The chief sources of supply are the 
Amazon valley (Para rubber, the product of Hevea brasi- 
liensis), the Ceara Province of Brazil (Ceara rubber, Manihot 
Glaziovii), Central America (Columbian, Panama, Mexican, 
Nicaragua, Centrals, Ac., Castilloa elastica ), West Africa 
and Congo (Senegal, Sierra Leone, Gaboon, Angola, Ac., 
species of Landolphia, Funtumia elastica , Ac.), Madagascar 
(Landolphia ), Assam ( Ficus elastica ), Borneo ( Willughbeia 
firma), and other islands of the Malay Archipelago. 
Rubber appears on the market in many forms, known as 
slabs, balls, lumps, tongues, biscuits, sheets, twists, strips, 
negrohead, niggers, scrap, Ac. The qualities first named 
are in general the best, being more homogeneous and less 
intermixed with bark, sand, or other impurities. The price 
varies from about 4s. 6d. per lb., which is obtained at present 
by the biscuits of the finest Ceylon-grown Hevea rubber, 
down to about Is. 6d. for poor scrap rubbers. The standard 
rubber quality is “ Fine Para, up-river, hard cure,” which 
