27 
Description of Figures. —Fig. 1, a med of Agaricus (Armil- 
laria) melleus, Vahl, nat. size; 2, sect of a fungus, showing 
the gills running for some distance down the stem (decurrent) 
and producing at the base of the stem black cord-like strands of 
mycelium or rhizomorphs ; nat. size 
DCXL.—ARTIFICIAL PRODUCTION OF INDIA- 
RUBBER. 
India-rubber, or caoutchouc, is chemically a hydrocarbon. But 
what is called pm molecular constitution is unknow All that 
has been ascertained is that when decomposed by heat (distillation 
in elosed vess ssels) 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 
natives of tropical countries, As is well known, it occurs in the 
latex, a milky juice contained in the laticiferous vessels. It is not 
dissolved in the latex but is merely suspended in 
All chemical substances of vegetable origin sooner or later yield 
to the art of the synthetic chemist, and admit, therefore, of being 
built up from simplercompounds. The methods of accomplishing 
this in individual cases may or may not lead to commercial results. 
In many cases they remain merely of theoretical interest as, 
though PIERDE they are too cumbrous and expensive to be of 
actual uti 
The itid production of every organic compound is, then, 
a scientific problem which may have commercial results. It is 
always a matter of interest to note and place on record the first 
step towards its solution, although the commercial application 
may be remote. 
Such a first step has been achieved by Dr. Tilden, F.R.S., 
Professor of Chemistry in the Royal College of Science, South 
Kensington, in the case of india-rubber. He has kindly permitted 
^M republication of his results in these pages with some more 
ecent revisions. They have also been republished in the 
Chemical News. 
* Note on the Spontaneous Conversion of Isoprene into 
Caoutchouc. 
* [Read before the Mio res Philosophical Society, 
y 18th, 1892.] 
= wears isa hydrocarbon ek was discovered by Greville 
Williams many years ago among the qp of the destructive 
distillation e iy abhor eda in 1884 (Trans. Chem. Soc 
vol. 45, p. 410), it was observed by myself among the more 
vola tile compounds obtained by the action of a moderate heat 
upon oil of turpentine and other terpenes. It isa very volatile 
3282 A2 
