hydrochloric acid. The artificial preparation of theobromine and
caffeine from xanthine, and guanine also show clearly their relations.

If, having completed our survey of what has been done in the way of
decomposing the alkaloids by the different classes of reagents, we
review the field, it will be seen that with all the alkaloids mentioned,
except the last four, a more or less immediate connection with the
pyridine and quinoline bases has been indicated. The conviction
accordingly forces itself upon us that, if we want to attack the problem
of building up any of these important alkaloids artificially, we must
turn to these bases as our starting point.

As already stated, both series occur in coal-tar and the pyridine series
also more abundantly in bone-oil. Pyridine, picoline, lutidine, and
collidine, the first four members of the pyridine series, have,
moreover, all been formed synthetically, although the processes are not
such as would yield the products as cheaply as they can be gotten from
Dippel's oil. Quinoline, the first member of the higher series, had been
made synthetically by several chemists, but by expensive and involved
methods, when Skraup, in 1881, effected its synthesis from nitrobenzol
and glycerin, or still better, a mixture of nitrobenzol and aniline with
glycerin. This process allows of its being made on a commercial scale if
desirable. Shortly after, by an application of the same principle,
Dobner and Miller effected the synthesis of lepidine, the second member
of the quinoline series.

At the same time that this general agreement to consider these bases as
the starting point in the endeavor to effect the synthesis of the
natural alkaloids had been arrived at by chemists, it was thought well
to look into the question whether these bases and their immediate