147 
am not aware of any native india-rubber with an acid re- 
action ; even the juice of the Para rubber tree, Hevea brasiliensis, 
is distinetly alkaline when drawn, and exhales a strong smell of 
i he be m this rce is strong i 
given off, which probably, by neutralizing the ammonia, 
brings about the coagulation of the caoutchouc, the excess of acid 
the roasting of the nuts may help to explain the acid 
product could be improved by precipitation with ordinary crude 
acetic acid, which at the same time would arrest those changes 
which are liable to go on afterwards to the detriment probably of 
the rubber, is worth finding out. I thought it would be important 
to ascertain whether the soft clammy condition of the samples was : 
due to oxidation, or to the presence of resinous matter. A white 
pulverulent resin was obtained from sample No. 4, amounting to 
24:48 per cent. of its weight. The caoutchouc, by destructive 
cures quite solid, but soft and short; this may be due to the 
resinous matter. The oxidation of the rubber itself will not 
account for it. The rubber may be hardened by pigments, but 
its strength is still very low, It can be mixed with other low-class 
rubbers with a corresponding improvement in toughness and 
strength. 
present case. 
I was informed by a friend who spent some time in Africa, that 
a very large quantity of crude acetic acid was shipped to different 
parts on the Kast Coast some years ago and was evidently used in 
. preparing india-rubber. - 3 | a 
25781 E2 
