179 
latex.* The alkaline properties of this extract are well known 
to the native Indians, who frequently employ it in the manufac- 
ture of soap. The latex has an acid reaction iss litmus 
latio 
Coagulation may also be eme about $: ‘roiling the latex, as, 
for example, in the preparation of * balat from Mimusops 
miey in Venezuela and Trinidad. 
here are several other methods in general use besides the few 
that have been quoted, and many others have been suggested from 
time to time 
r exists in particles in the latex, it ponas possible 
that the BRAA method of separation might adopted in 
examining the phenomena of coagulation, A "modio d form of 
the ordinary centrifugal milk-tester was, therefore, designed 
capable of being rotated some 6,000 times per minute. 
The latex was n n directly from the trees, strained through 
wire gauze to remove any pieces of bark, and then, if very thick, 
diluted to about ihe consistency of thin cream. The first experi- 
ments were made with the latex of IRAE elastica. | After 
centrifugalizing for from three to four minnis the rubber- 
particles completely separated as a thick, creamy, white layer, 
from the deep brown solution containing dime c acid in which 
they had been suspended. This layer was taken off, shaken with 
an excess of water to thoroughly wash it, and again separated. 
y 
n lo 
several days. The particles couid, however, be brought into a 
solid mass by pressure, by gently heating, or by drying off the 
water with a porous tile. 
So prepared, the rubber formed a pure ag mass, without any 
trace of its usually characteristic smell. On ;exposure to the a 
for "s days, the surface became locum probably owing to 
oxidatio 
The percentage of rubber in the latex was estimated at the same 
time by — ing 50 c.c. The weight of the dry substance was 
1255 grammes, which; as the specific gravity of Castilloa elastica 
latex is practically 1-0, gives a yield of 25 per cen 
On treating the latex of Hevea bi WHAtRAD SHE in the ho malon, ERE OF for 
* Belt, Naturalist i in — ua, : 
t For a complete account, ie UD et la Gutta-percha, Seeligman, 
Lamy, and Falconnet, Paris, 1896. 
378 A2 
