16 
that the rubber-particles, owing to their being sticky bodies 
unprotected by any external film, as e.g., the fat-partieles of milk 
are, are capable of aggregating together of their own accord to 
o olid mass. 
Rubber then, as now prepared, contains among other substances 
proteid matters. To these must be ascribed the well-known 
: 8 
smoke of the burning nuts acts as an antiseptic and prevents this 
proteid decomposition.* 
for the coagulated proteids is not an easy mattte 
tai 
R. H. BIFFEN. 
Botanical Laboratory, Cambridge. 
February, 188. 
VL—ARTIFICIAL PRODUCTION OF INDIA- 
RUBBER. 
[ K.B., 1399, pp. 27, 28.] 
India-rubber, or caoutchouc, is chemically a hydrocarbon. But 
what is called its molecular constitution is un nown. that 
has been ascertained is that when decomposed by heat (distillation 
in closed vessels) it is broken up into simpler hydrocarbons, 
amongst which is isoprene. 
Caoutchouc is found in a considerable number of plants in no 
way related by botanical affinity. But they are for the most part 
. All chemical substances of vegetable origin sooner or later yield 
In many cases they remain merely of theoretical interest as, 
though practicable, they are too cumbrous and expensive to be of 
actual utility. 
The artificial production of every organic compound is, then, 
a scientific problem which may have commercial results. It is 
mot HE SIUS BISHQUENISESADSSHGU TUQUE M UE 
* Cf., the smoking of fish. &o., for preserving purposes, 
