178 
purpose in the Sois cmd san anical Gardens. The results 
obtained were of some interest, and accordingly the experiments 
were d ic her with ner researches on a larger scale, 
in Mex o, Brazil, and the West Indian Islands. 
Bubber-yielding plants, which always have peces, cells, 
were for the most part chosen on account of the e 
large quantities of latex could be obtained, and boots the various 
processes used in the preparation of crude rubber seemed likely 
ject. 
A microscopic examination of any of these latices shows that 
its milky appearance is due to the presence of innumerable small 
granules of caoutchouc, which in themselves are soft and sticky. 
for they readily cohere to form a small mass of rubber if the 
sp is ape is lightly rubbed on the slide. 
Some of the processes employed to prepare this rubber may be 
desorbed ere. 
In the preparation of Para epis athin layer of the latex of 
Hevea He cies (Muell. Arg.) or other species of Hevea, is 
exposed to the action of the smoke at burning “ urucuri " nuis 
(Attalea excelsa, Mart.); coagulation is mm ediately brought 
about, resulting in the formation of a soft, curdy mass of rubber, 
which on drying becomes tough and ela 
The same process is now being applied with good results to the 
preparation of Ceara rubber from the latex of “Manihot Glaziovii 
(Muell. Arg.). 
The usually accepted Erp anaon of this is that the water 
contained in the latex is simply evaporated off;* but as the 
coagulation i is brought about in so short a time, and moreover as 
there is no loss of weight on its occurrence, this is "opviodels 
incorrect. 
On passing the smoke of the burning Attalea nuts through a 
condenser, condensation occurs, and two layers of liquid are found 
in the receiver, one colourless and limpid, the other dark brown 
and oily. If these are separated by means of a pipette, or with a 
moistened filter paper, and analyzed, the former is found to 
consist mainly of acetic acid, and the latter of creosote and traces 
of pyridine derivatives. 
On adding acetic acid to the crude latex. of Hevea coagulation 
e 
quote 
It orthy of note that the latex of Hevea brasiliensis is in 
itself pir and that the addition of a solution of ammonia 
preserves it indefinitely from spont Nie coagulation. The 
addition of alkalies brings about coagulation, however, in the latex 
of Castilloa elastica. In Mexico and Nicaragua, where this tree 
abounds, a decoction is made of the stems of ihe Moonflower 
Ipomoea Bona-noz (Calonyction speciosum), and added to the 
* Ernst, Trinidad Bulletin, vo. i ie = 
+ Kew Bulletin, 1890, Art. 142, p. 89. 
i Watt's Diet. Economie Pola of India, vol. iv., p. 343, 
