18 
“A solution of the artificial rubber in benzene leaves on 
evaporation a residue whic E s in all characters with a similar 
preparation from Para-rubber 
“ The artificial rubber ORE with sulphur in the same way as 
moraery rubber, forming a tough elastic compound. 
“The constitutional formula of DH is now known to be :— 
Methyl-crotonylene, C =C€ 
“It is obvious that fT such . as gere containing 
doubly-linked carbon, may polymerise in a variety of ways; and, 
in the present condition of our knowledge even of in we i 
would be idle to speculate as to which out o ume 
possible arrangements would correspond. to the Sonsdiqtion of 
eaoutchouc."—(Proc. Birm. Phil. Soc. viii., Pt. try 
In a recent letter Professor Tilden states :—' As you 
inagine, I have tried everything I can think of as likely 
promote this change, but without success. The Kok Sibel 
proceeds very slowly, occupying, according to my experience, 
several years, and all attempts to hurry it result in the production 
not of rubber but of ‘colophene,’ a thick sticky oil quite useless 
for all the purposes to which rubber is applied.” 
VIL—GUTTA PERCHA FROM A CHINESE TREE. 
(Eucommia ulmoides, Oliv.) 
[K.B., 1901, pp. 89-94.] 
Between 1887 and 1890, from several localities on the middle 
he adds, *but I was informed it ‘occurs so in Fang and other 
districts to the north.” Fang is the name of a region near the 
middle part of the Yangtze-Kiang in the province of Hupeh. 
This plant Prof. D. Oliver described (Hooker’s Icones Plantarum, 
t. da as Hucommia ulmoides 
S. 
Flow not being 2i agas Ana what material he had so 
ME that its aeos aer ips were not eias Prof. Oliver left 
the determination of the order of Tu ucommia open, merely siding 
that the tribe Phyllantheae of Ern cta occurred to him 
of probable affinity. 
The interest to us lies not so much in this as in his indication 
of the presence in the tissues of gutta percha. The discovery he 
made known in c following words :— E a 
perhaps the w per,—in the bark (in the usual sense of the 
word), the leaves and poem dde pericarp; any of these, snapped 
across, and the parts drawn ay exhibit the silvery 'sheen of 
innumerable d of this sra 
