experimental
obstacles, and organic chemistry had now become synthetic.

Liebig and Wohler, in 1837, foresaw the artificial production in the
laboratories of all organic substances so far as they did not
constitute a living organism. And after fifty years their prophecy had
been fulfilled, for at the present time we could prepare an artificial
sweetening principle, an artificial alkaloid, and salacine.

SYNTHESIS.

We know now that the same laws regulate the formation of chemical
compounds in both animate and inanimate nature, and the chemist only
asked for a knowledge of the constitution of any definite chemical
compounds found in the organic world in order to be able to promise to
prepare it artificially. Seventeen years elapsed between Wohler's
discovery of the artificial production of urea and the next real
synthesis, which was accomplished by Kolbe, when in 1845 he prepared
acetic acid from its elements. Since then a splendid harvest of
results had been gathered in by chemists of all nations. In 1834 Dumas
made known the law of substitution, and showed that an exchange could
take place between the constituent atoms in a molecule, and upon this
law depended in great measure the astounding progress made in the wide
field of organic synthesis.

Perhaps the most remarkable result had been the production of an
artificial sweetening agent, termed saccharin, 250 times sweeter than
sugar, prepared by a complicated series of reactions from coal tar.
These discoveries were not only of scientific interest, for they had
given rise to the industry of coal tar colors, founded by our
countryman Perkin, the value of which was measured by millions
sterling annually. Another interesting application of synthetic
chemistry to the needs of everyday life was the discovery of a series
of valuable febrifuges, of which antipyrin might be named as the most
useful.

An important aspect in connection with the study of these bodies was
the physiological value which had been found to attach to the
introduction of certain organic radicals, so that an indication was
given of the possibility of preparing a compound which will possess
certain desired physiological properties, or even to foretell the kind
of action which such bodies may exert on the animal economy. But now
the question might well be put, Was any limit set to this synthetic
power of the chemist? Although the danger of dogmatizing as to the
progress of science had already bee