ELASTIC SUBSTANCE ON SHOOTS AND YOUNG LEAVES. 141 
allowed to remain in this for 5 days. Previous investiga- 
tion had shown that other ordinary solvents, such as 
benzene, ether, acetic-ether, alcohol, acetone, toluene and 
essential oils, had little action upon the caoutchouc in the 
cold, although it was much swollen by several of them; 
even carbon disulphide appeared to have little action upon 
it. Chloroform was the only solvent which was found to 
act at all satisfactorily. After 5 days the chloroform was 
mostly distilled off, the remainder transferred to an open 
vessel and allowed to evaporate spontaneously. The 
residue, when dry, was quite elastic and slightly coloured 
green from the presence of a small amount of chlorophyl. 
It resembled in appearance and ordinary general characters, 
the crude caoutchouc or “‘India-rubber’’ of commerce. Its 
chemical reactions were also found to be similar. The 
amount of substance extracted by chloroform after 5 days 
was, when dry, 0°785 gram, equal to 0°157*. 
There still remained a considerable amount of the elastic 
substance attached to the leaves, and it was much swollen 
by its contact with the chloroform. It was largely 
recovered by the following process :—After the chloroform 
had evaporated from the material, it was steeped in a 5% 
aqueous solution of potash for 5 days. At the end of that 
time the structure of the leaf had become largely decom- 
posed, or so much softened that by continued washing and 
kneading it was entirely washed away. The caoutchouc 
had been quite unacted upon by the alkaline solution, and 
it adhered together slightly so that it was eventually 
obtained in a fairly pure condition. The stalks and stems 
were easily squeezed or picked out as the mass was kneaded 
together in the hand. By this method 1°55 gram of elastic 
substance was obtained, equal to 0°31. The chloroform 
extract represented the whole of the substance dissolved, 
but some of the remainder was unavoidably lost as the leaf 
