s which they furnish. If
the descriptive details are devoid of romance to the general reader, the
results achieved in the short period of thirty-five years, dating from the
discovery of mauve by Perkin, will assuredly be regarded as falling but
little short of the marvellous. Although the most striking developments
are naturally connected with the colouring-matters, whose history has been
sketched in the foregoing pages, and whose introduction has revolutionized
the whole art of dyeing, there are other directions in which the coal-tar
industry has in recent times been undergoing extension. Certain
tar-products are now rendering good service in pharmacy. Salicylic acid
and its salts have long been used in medicine. By distilling a mixture of
the dry lime salts of benzoic and acetic acids there is obtained a
compound known to chemists as acetophenone, which is used for inducing
sleep under the name of hypnone. The acetyl-derivative of aniline and of
methylaniline are febrifuges known as "antifebrine" and "exalgine." Ethers
of salicylic acid and its homologues, prepared from these acids and
phenol, naphthols, &c., are in use as antiseptics under the general
designation of "salols."

In 1881 there was introduced into medicine the first of a group of
antipyretics derived from coal-tar bases of the pyridine series. It has
already been explained that this base is removed from the light oil by
washing with acid. Chemically considered, it is benzene containing one
atom of nitrogen in place of a group consisting of an atom of carbon and
an atom of hydrogen. The quantity of pyridine present in coal-tar is very
small, and no use has as yet been found for it excepting as a solvent for
washing anthracene or for rendering the alcohol used for manufacturing
purposes undrinkable, as is done in this country by mixing in crude
wood-spirit so as to form methylated spirit. The salts of pyridine were
shown by McKendrick and Dewar to act as febrifuges in 1881, but they have
not hitherto found their way into pharmacy. The chief interest of the base
for us centres in the fact that it is the type of a group of bases related
to each other in the same way as the coal-tar hydrocarbons. Thus in
coal-tar, in addition to pyridine, there is another base known as
quinoline, which is related to pyridine in the same way that naphthalene
is related to benzene. Similarly there is a coal-tar base known as
acridine, which is found associated with the anthracen