gas masks in the latter part of the war were made without rubber and
were frail and leaky. They could not have withstood the new gases which
American chemists were preparing on an unprecedented scale. Every scrap
of old rubber in Germany was saved and worked over and over and diluted
with fillers and surrogates to the limit of elasticity. Spring tires
were substituted for pneumatics. So it is evident that the supply of
synthetic rubber could not have been adequate or satisfactory. Neither,
on the other hand, have the British made a success of the Perkin
process, although they spent $200,000 on it in the first two years. But,
of course, there was not the same necessity for it as in the case of
Germany, for England had practically a monopoly of the world's supply of
natural rubber either through owning plantations or controlling
shipping. If rubber could not be manufactured profitably in Germany when
the demand was imperative and price no consideration it can hardly be
expected to compete with the natural under peace conditions.

The problem of synthetic rubber has then been solved scientifically but
not industrially. It can be made but cannot be made to pay. The
difficulty is to find a cheap enough material to start with. We can make
rubber out of potatoes--but potatoes have other uses. It would require
more land and more valuable land to raise the potatoes than to raise the
rubber. We can get isoprene by the distillation of turpentine--but 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