CAOUTCHOUCS OR 
IARUBBERS (Gastilloa). 
For the majority of its uses rubber is vulcanized, a certain 
proportion of sulphur being added to it during mastication 
and the rubber heated for some time to a considerable 
temperature. It thus becomes tougher and more resistent, 
and is less easily melted. A larger proportion of sulphur 
(20-40 per cent.) produces vulcanite or ebonite. 
A.—STAPLE RUBBERS. 
f CASTILLO A OR PANAMA RUBBER.— Gcistilloa, 
is a genus of the family Moracece (often included in 
I 'UrticacecB ), and belongs to that section of the family which 
includes the jak and breadfruit ( Artocarpus ), the milk tree 
(Brosimum ), and the many species of Ficus , esj., the Bo and 
the Assam rubber (F. elastica). The g>enus has two or more 
species. Of these, the most important is G. elastica , Cervan¬ 
tes, the Ule of the Spaniards, which is found wild in Mexico 
from lat. 21° southwards, in Guatemala, Honduras, San Sal¬ 
vador, Costa Rica, and Nicaragua; it also appears to occur in 
North-Western South America. G. tunu Hemsl., the Tunu, 
occurs in Honduras and Costa Rica. CastiUoa rubber was 
introduced into the Colony about the same time as the Para 
and through the same agency. A Wardian case of plants 
arrived in 1876 from the Royal Gardens, Kew, and the plants 
were put out at Henaratgoda and Peradeniya. .They grew 
well at both places, but especially at Henaratgoda, and were 
increased by cuttings. They began to flower in 1881, and in 
the following year a few seeds were ripened. About 1886 
the growth became less rapid, and since then has been very 
slight, the soil in the gardens being shallow, and at Henarat¬ 
goda not well drained. G. elastica is usually described as a 
large tree of rapid growth, reaching 180 feet in height and 15 
feet in girth. The Ceylon plants show no sign of such 
growth. There has been some doubt as to whether they 
are the true G. elastica; they were brought by Cross from 
Darien (Panama), where they were locally known as Caucho? 
and have been described by some as a different species, G. 
