CHINOLINE AND ITS HOMOLOGIES. 381 



of which exist, the first being the correctness of the old formula for chinoline (or 

 leukol), the second, its being the sole basic product in the distillate, from the 

 cinchona alkaloids. 



The next prevalent error with regard to chinoline is, that its salts have less 

 tendency to crystallize than the generality of nitryl bases ; whereas, in fact, the 

 reverse (with some exceptions) is the truth. I have seldom seen salts more 

 easy to crystallize than the nitrate, oxalate, and bichromate of chinoline, while its 

 double salts, with platinum, gold, palladium, uranium, and cadmium, are beauti- 

 ful substances, the same may be said of the iodides of the methyl, ethyl, and amyl 

 compounds. The erroneous idea alluded to arose from previous experimenters, 

 working on an impure substance. 



The only means for determining the constitution of chinoline up to the present 

 time, has been Dr Hofmann's analysis of the platinum salt, from a base extracted 

 from coal-tar ; for the combustions of the base itself yet made, are very unsatis- 

 factory. Annexed are the results as yet obtained.* 



Carbon, . 

 Hydrogen, 

 Nitrogen, 





HoFMANN. 





Bromeis. 



C 18 H 7 N 



83-70 



5-41 



10-89 



C 20 H 9 N 



82-67 



6-56 



11-28 



82-88 

 6-25 



82-34 

 6-10 



82-74 82-78 

 6-11 5-88 



83-91 

 6-29 

 9-80 



100-00 100-00 



A glance at the above numbers shows that no conclusion can be drawn from 

 them ; and when it is considered, that chinoline and lepidine only differ by "21 in 

 their percentage of carbon, it becomes evident, that careful analyses of the salts 

 of these bases are the only means by which their history and composition can be 

 rendered certain. The platinum salt of chinoline possesses characters which 

 render it peculiarly well adapted for this purpose, inasmuch as it differs totally 

 from the corresponding compound from the Dippel and aniline series, in its great 

 insolubility. I therefore selected this compound as a means of ascertaining the 

 purity of the various fractions obtained in the course of the investigation, and 

 which were intended for conversion into the various salts described further on ; 

 sometimes I was contented with merely a platinum determination, at others, I 

 ascertained by combustion with chromate of lead, the percentage of carbon and 

 hydrogen, and in this manner, the analyses quoted below were obtained. In my 

 former paper, I gave the result of three combustions of the platinum salt of chino- 

 line, and three platinum determinations ; the salts analysed were obtained from 

 fractions boiling at a somewhat lower temperature than those the details of the 

 analyses of which are given below. The following analyses were made with salts 

 obtained from fractions boiling about 460°, which is, probably, very nearly the 

 boiling point of chinoline. 



* Gerhardt, Traite, troisieme partie, p. 149. 

 VOL. XXI. PART III. 5 L 



