ELASTIC SUBSTANCE ON SHOOTS AND YOUNG LEAVES, 143 
rubbers. On continued heating it ignited, burning with 
a very luminous flame which was less smoky than that 
from ordinary rubbers. When the carbon was burnt away 
a small amount of a dark coloured ash remained. Heated 
in a closed tube a light coloured liquid (which remained 
quite fluid when cold) distilled off, leaving a small amount 
of a carbonaceous residue. When treated with concen- 
trated sulphuric acid the caoutchouc was eventually 
decomposed, forming a clear and slightly fluorescent 
solution. Nitric acid in the cold slowly acted upon it, 
eventually largely decomposing it with the formation of a 
yellow coloured solution. Dilute acids had no action upon 
it. When heated for some time in melted sulphur, it 
became vulcanized similarly to ordinary rubber. It was 
then more elastic than in the original state, and was grey 
in colour. The method adopted was necessarily crude, yet 
the result was sufficient to show that it would vulcanize 
very well. 
An analysis of the caoutchouc extracted by chloroform 
and heated at 100-—110° gave the following:—0°2001 gram 
gave 0°5846 gram CO, and 0°1925 H,O. The ash left in 
boat weighed 0°0007 gram, equal to 0°349% so that 0°1994 
gram was burnt away. The percentage of H=10°73 and 
©. 79°9. The presence of 9°37% of oxygen indicates the 
rapidity of natural oxidation. Of course no formula can 
be arranged, as the alteration is evident, but it is worthy 
of notice that the hydrogen and the carbon still roughly 
approximate the terpene formula. 
From the above investigations it is apparent that the 
elastic substance occurring in the shoots and young leaves 
of Eucalyptus corymbosa, Angophora lanceolata and 
A. intermedia is a good form of caoutchouc. There isa 
comparative absence of the viscous form which occurs in 
ordinary crude ‘rubber.’ This is indicated by its high 
