ut why
not bleed a rubber tree as well as a pine tree? Turpentine is neither
cheap nor abundant enough. Any kind of wood, sawdust for instance, can
be utilized by converting the cellulose over into sugar and fermenting
this to alcohol, but the process is not likely to prove profitable.
Petroleum when cracked up to make gasoline gives isoprene or other
double-bond compounds that go over into some form of rubber.

But the most interesting and most promising of all is the complete
inorganic synthesis that dispenses with the aid of vegetation and starts
with coal and lime. These heated together in the electric furnace form
calcium carbide and this, as every automobilist knows, gives acetylene
by contact with water. From this gas isoprene can be made and the
isoprene converted into rubber by sodium, or acid or alkali or simple
heating. Acetone, which is also made from acetylene, can be converted
directly into rubber by fuming sulfuric acid. This seems to have been
the process chiefly used by the Germans during the war. Several carbide
factories were devoted to it. But the intermediate and by-products of
the process, such as alcohol, acetic acid and acetone, were in as much
demand for war purposes as rubber. The Germans made some rubber from
pitch imported from Sweden. They also found a useful substitute in
aluminum naphthenate made from Baku petroleum, for it is elastic and
plastic and can be vulcanized.

So although rubber can be made in many different ways it is not
profitable to make it in any of them. We have to rely still upon the
natural product, but we can greatly improve upon the way nature produces
it. When the call came for more rubber for the electrical and automobile
industries the first attempt to increase the supply was to put pressure
upon the natives to bring in more of the latex. As a consequence the
trees were bled to death and sometimes also the natives. The Belgian
atrocities in the Congo shocked the civilized world and at Putumayo on
the upper Amazon the same cause produced the same horrible effects. But
no matter what cruelty was practiced the tropical forests could not be
made to yield a sufficient increase, so the cultivation of the rubber
was begun by far-sighted men in Dutch Java, Sumatra and Borneo and in
British Malaya and Ceylon.

Brazil, feeling secure in the possession of a natural monopoly, made no
effort to compete with these parvenus. It cost about as much to gather
rubber from the Amazon