f chemistry
was the discovery by an English professor that a substance
corresponding in every respect to India rubber may be produced from
oil of turpentine.

Dr. W. A. Tilden, professor of chemistry in Mason College, Birmingham,
began a series of experiments with a liquid hydrocarbon substance,
known to chemists as isoprene, which was primarily discovered and
named by Greville Williams, a well known English chemist, some years
ago as a product of the destructive distillation of India rubber. In
1884, says The New York Sun, Dr. Tilden discovered that an identical
substance was among the more volatile compounds obtained by the action
of moderate heat upon oil of turpentine and other vegetable oils, such
as rape seed oil, linseed oil and castor oil.

Isoprene is a very volatile liquid, boiling at a temperature of about
30 degrees Fahrenheit. Chemical analysis shows it to be composed of
carbon and hydrogen in the proportions of five to eight.

In the course of his experiments Dr. Tilden found that when isoprene
is brought into contact with strong acids, such as aqueous
hydrochloric acid, for example, it is converted into a tough elastic
solid, which is, to all appearances, true India rubber.

Specimens of isoprene were made from several vegetable oils in the
course of Dr. Tilden's work on those compounds. He preserved several
of them and stowed the bottles containing them away upon an unused
shelf in his laboratory.

After some months had elapsed he was surprised at finding the contents
of the bottles containing the substance derived from the turpentine
entirely changed in appearance. In place of a limpid, colorless liquid
the bottles contained a dense sirup, in which were floating several
large masses of a solid of a yellowish color. Upon examination this
turned out to be India rubber.

This is the first instance on record of the spontaneous change of
isoprene into India rubber. According to the doctor's hypothesis, this
spontaneous change can only be accounted for by supposing that a small
quantity of acetic or formic acid had been produced by the oxidizing
action of the air, and that the presence of this compound had been the
means of transforming the rest.

Upon inserting the ordinary chemical test paper, the liquid was found
to be slightly acid. It yielded a small portion of unchanged isoprene.

The artificial India rubber found floating in the liquid upon analysis
showed all the constituents of natural rubb