ON THE COMMERCIAL KINDS OF INDIA-RUBBER. 3 
coalescing together and leaving a thin fluid behind. In several bottles 
of milk, Thompson found that though they were hermetically sealed, 
yet about 40 per cent. of the contents had separated, in the form of a 
lining of caoutchouc. Faraday was more fortunate in obtaining 
bottles in which only about the proportion of one-fifth had separated 
in the form of caoutchouc, the liquid being of a pale yellow colour, 
thick, like cream, and forming a solid sheet of caoutchouc when poured 
on any solid substance. Pure india-rubber is of a pale yellow colour, 
having no taste or smell; the colours found in the commercial varie- 
ties resulting either from admixture of bark, atmospheric influence, 
etc. At 32° it is hard and very slightly elastic, at 60° to 70° soft and 
pliable. 
I. AMERICAN KINDS OF INDIA-RUBBER. 
One of the earliest notices of the use of india-rubber is given by 
Herrera in his account of Columbus's second voyage ; where, speaking 
of the natives of Hayti, he says, “They had other amusements, 
such as the game of ball, for which they had a house set apart, and 
they played it so many on each side, without stieks or bats, for they 
struck the balls with any part of their bodies, and with great dexterity 
and nimbleness. And the balls were of the gum of a tree, and although 
large, were lighter and bounced better than the bipes of Castile.” 
(Herrera, Historia, decada i., libro iii., cap. i 
The first account of a tree yielding Ses ALES TP 
Cerv.—is given by Torquedama, whose work was published in the latter 
end of the sixteenth century, and who, speaking of Mexico, says :— 
‘There is a tree which the Indians call Ulequahuitl; it is held in great esti- 
mation, and grows in the hot country. is not a very high tree; the leaves 
re round and of an ashy colour. This tree yields a white milky substance, 
thick and gummy, and in great abundance. To obtain it, the tree is wounded 
with an axe or cutlass, and from these wounds the liquid drops. The natives 
collect it in round vessels of different sizes, called, in their language, Xicalli, 
but by us calabashes. In these they allow it to settle in round balls of the 
size most convenient for the purposes to which they are about to apply them. 
When quite set they boil them in water, in which state the gum is called Ulli. 
The Indians who have got no calabashes, smear their bodies over with it (for 
Nature is never without a resource), and when it becomes dry they remove the 
whole incrustation, which comes off in the form of a very smooth membrane, 
its thickness depending on the will of the party collecting. They then make 
* For a translation of this account, and many other useful hints, I am in- 
debted to Dr. Spruce. 
B 2 
M until 
