396 MR C. G. WILLIAMS' RESEARCHES ON 



mention, that by this treatment, the boiling point of the bases was considerably 

 raised, the aniline being removed, which boils 100° below chinoline. 



The bases, as purified by the above method yield, on distillation, fractions 

 from 350° to 525°, Considerably more than one hundred distillations were 

 made before sufficient separation had taken place, to justify me in making any 

 analyses. 



Chinoline having already been proved to exist in coal-tar, I began the experi- 

 ments by searching for lepidine. This base, which was discovered by me* among 

 the volatile alkaloids procured by distilling cinchonine with potash, has the 



formula, 



C 20 H 9 N, 



which was established by analyses of the platinum salt, nitrate, hydrochlorate, 

 and bichromate, confirmed also by a determination of its vapour density. 



As obtained from coal-tar, lepidine is in the form of an oil, having an odour 

 almost exactly the same as that from cinchonine. But it is impossible by distil- 

 lation alone, even after the treatment of the crude base with nitrous acid, to 

 procure it in the same state as from the source where it was first found. Coal- 

 lepidine, therefore, yields salts which, for the most part, crystallize with in- 

 comparably greater difficulty than that from cinchonine. When dissolved in an 

 acid, although the solution is perfect, there is always an after-odour evolved, 

 somewhat like naphthaline, unless the base has been purified with great care. 

 I was unable, by any means at at my disposal, to obtain the bichromate in a crys- 

 talline state, whereas the lepidine from cinchonine yields a beautiful salt, in 

 brilliant yellow needles half-an-inch long. Even when coal-lepidine is boiled with 

 diluted chromic acid for an hour, the base, when separated and redistilled, gives 

 an oily precipitate with chromic acid ; moreover, the same occurs if the base be 

 dissolved in hydrochloric acid, and a solution of bichromate of potash is added, 

 as has been previously mentioned in describing the bichromate of chinoline. The 

 red oil obtained in this manner from coal-lepidine may be kept for weeks without 

 showing any tendency either to crystallize or decompose ; even the base obtained 

 from a platinum salt of considerable purity, behaved in the same way. On the 

 other hand, coal-lepidine reacts with nitric acid and some other re-agents, like 

 that from cinchonine. 



If it were not for the decisive manner in which the fact of Dr Hofmann's having 

 obtained the crystalline precipitate with leukol and chromic acid has been an- 

 nounced, I should have felt justified in asserting that the bases derived from the 

 two sources were isomeric but not identical ; but as the last-named chemist's well- 

 known accuracy prevents me from entertaining a belief in the possibility of an error 

 of experiment, I can only express my regret, that I am ignorant of the method of 



* Trans. Royal Soc. Edin., vol. xxi., pt. 27. 



