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 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 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 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{5}H{5}N, and quinoline, C{9}H{7}N, respectively, bear to each other a relation analogous to

that existing between benzol, C{6}H{6}, and naphthalene, C{10}H{8}; and the theory generally accepted by those chemists who have been occupying themselves with these bases and their derivatives is that pyridine is simply benzol, in which an atom of nitrogen replaces the triad group, CH, and quinoline, the naphthalene molecule with a similar change.

The same thing applies to quinoline as compared to naphthalene.

Morphine, rapidly distilled over zinc dust, yields phenanthren, trimethyl-amine, pyrrol, pyridine, quinoline, and other bases.

When distilled with potassium hydrate, quinine yields quinoline and its homologues.

Cinchonine, C{19}H{22}N{2}O, the second most important alkaloid of these barks, when oxidized with potassium permanganate, yields cinchonic acid, which is a quinoline-carboxylic acid, C{9}H{6}N(COOH), cinchomeronic acid, which has just been stated to be a pyridine dicarboxylic acid, and a pyridine tricarboxylic acid.

When cinchonine is treated with potassium hydrate, it is decomposed into quinoline and a solid body, which on further treatment yields a liquid base, C{7}H{9}N, which is probably lutidine.

It has been found, moreover, that both tetrahydroquinoline and dihydroquinoline, hydrogen addition products of quinoline, are present.

When cinchonine is distilled with solid potassium hydrate, it yields pyrrol and bases of both the pyridine and quinoline series.

Cinchonidine, when heated with potassium hydrate, yields quinoline also, and with nitric acid the same products as cinchonine.

When distilled with potassium hydrate, quinoline is formed.

When distilled with potassium hydrate it yields quinoline, lutidine, and two isomeric collidines.

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.

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.

Shortly after, by an application of the same principle, Dobner and Miller effected the synthesis of lepidine, the second member of the quinoline series.

Prof. Filehne, of Erlangen, who has studied a large number of these pyridine and quinoline derivatives, found, moreover, that the hydrochlorate of ethyl-piperidine had a physiological action quite analogous to that of conine.

The physiological action of quinoline itself has been studied quite extensively by Donath and others, and it was found that several of its salts were quite valuable febrifuges, acting very like quinine, and capable in cases of being used as a substitute for it.

In general, the hydrogen addition products were found to be more active than the simple base, an observation entirely in accord with the theory formed by Wischnegradsky, and by Konigs, as the result of the study of the decomposition products of the alkaloids, viz., the alkaloids are in general hydrogen addition products of pyridine and quinoline, or of the two bases combined.

Thus Prof. Filehne found that hydrochlorate of tetrahydroquinoline was much more energetic in its action than quinoline, but could not be used on account of a too powerful local effect.

The most decided febrifuge action, however was found by Prof. Filehne to reside in the hydrochlorate of oxyhydro-methyl-quinoline, introduced to public notice by Prof. O. Fischer under the name of "Kairin," and in the acid sulphate of tetrahydro-methylquinoline, introduced under the name of "Kairolin.

The study of the decomposition products of the cinchona alkaloids especially points quite distinctly to the probable existence in quinine of a hydrogen addition product of pyridine, in combination with a methyl-quinoline group.