India Rubber and Gutta Percha. 69 
men standing round in a circle, beat them down 
with their hands, and they rebound high above their 
heads. Much laughter and merriment accompany- 
ing the game. Two hundred and fifty years later 
the Mexican Indians were found not only using playing 
balls, but manufacturing the gum into articles of domestic 
use, such as helmets, shoes and water-proof fabrics. 
The first detailed information regarding its origin and 
application was published by La CONDAMINE, a French 
naturalist, who resided at Para, where the inhabitants 
were in the habit of making candle-like torches of it, 
and even bottles and play-balls. Eventually from time 
to time parcels of the gum reached Europe, and attempts 
were made to utilize the substance in a variety of ways. 
Little success, however, attended these attempts until 
the discovery of the principle of vulcanisation brought 
india-rubber, it may be said, into general use. By vul- 
canisation the material is so altered as to resist to a con- 
siderable extent the action of heat and cold. Pure un- 
vulcanised Caoutchouc at o deg. centigrade is rigid and 
unpliable, though when subject to a temperature of 100 
degs. it becomes so soft as to be almost valueless for any 
of the purposes to which vulcanised rubber is applied. 
Since this discovery the scope of its application has 
rapidly grown, till it now forms a highly important in- 
dustry. In the manufacture of scientific apparatus, and 
in the arts generally, it holds an unique place, and no 
known substance could be adopted as a substitute. 
Caoutchouc exists in the form of minute globules in 
the milky sap of the bark of the plants which I have 
named. It is composed only of carbon and hydrogen in 
