t has been done and
what seems likely to be accomplished in the near future.

It was early recognized that the alkaloids were complex amines or
ammonia derivatives. The more or less strongly marked basic character of
these bodies, the presence of nitrogen as an essential element, and,
above all, the analogy shown to ammonia in the way these bases united
with acids to form salts, not by replacement of the hydrogen of the
acid, but by direct addition of acid and base, pointed unmistakably to
this constitution. But with this granted, the simplest alkaloid
formulas, those of conine, C_{8}H_{17}N, and nicotine,
C_{10}H_{14}N_{2}, still showed that the amine molecule contained quite
complex groups of carbon and hydrogen atoms, and the great majority of
the alkaloids--the non-volatile ones--contained groups in which the
three elements, carbon, hydrogen, and oxygen, all entered. Hence the
difficulty in acquiring a knowledge of the molecular structure of those
alkaloids at all comparable with that attained in the case of other
organic compounds. Of course synthesis could not be applied until
analysis had revealed something of the molecular grouping of these
compounds, so the action of different classes of reagents was tried upon
the alkaloids. Before summarizing the results of this study of the
decomposition and alteration products of the alkaloids, a brief
reference to a related class of organic compounds will be of assistance
to those unfamiliar with recent researches in this field.

It is well known that in coal-tar is found a series of ammonia-like
bases, aniline or amido-benzol, toluidine or amido-toluol, and xylidine
or amido-xylol, which are utilized practically in the manufacture of the
so-called aniline dye-colors. It is perhaps not so well known that there
are other series of bases found there too. The first of these is the
pyridine series, including _pyridine_, C_{5}H_{5}N, _picoline_
(methyl-pyridine), C_{5}H_{4}N(CH_{3}), _lutidine_ (dimethyl-pyridine),
C_{5}H_{5}N(CH_{3})_{2}, and _collidine_ (trimethyl-pyridine),
C_{5}H_{2}N(CH_{3})_{3}. This series is also found in relatively larger
proportion in what is known as Dippel's oil, the product of the dry
distillation of bones.

The second series is the quinoline series, including _quinoline_,
C_{9}H_{7}N, _lepidine_ (methyl-quinoline), C_{10}H_{9}N, and
_cryptidine_ (dimethyl-quinoline), C_{11}H_{11}N. The two compounds
which give name to these series, pyridine, C_