CHINOLINE AND ITS HOMOLOGUES. 395 



to chinoline, develops much heat, and on evaporation at 212°, a crystalline mass 

 was obtained, but so deliquescent, as to be unfit for examination. 



On the Chinoline Series as it occurs in Coal-Tar. 



In my paper " On some of the Basic Constituents of Coal-Naphtha and on 

 Chrysene," I ventured to express a belief, that chinoline was not the only mem- 

 ber of the group to which it belongs present in coal-tar ; and feeling assured that 

 other homologues remained to be discovered, I was desirous of testing the accuracy 

 of the supposition. Owing to the kindness of Mr George Miller of Dalmarnock, 

 I was enabled to obtain fifty gallons of coal-oil of a very high boiling point, and 

 of a density greater than that of water. It was shaken with sulphuric acid to 

 extract the alkaloids, and the acid fluid after dilution with water was treated with 

 excess of lime, and distilled as long as any came over. As the amount of bases of 

 the Dippel series present, was not large, the product being of such a high boiling 

 point, I did not add potash to separate the more soluble portion, but only collected 

 that part which, from its density and insolubility, sank to the bottom of the fluid 

 accompanying it in the distillation. By means of a tap funnel, the basic-oil was 

 separated from the chief part of the water accompanying it, which contained some 

 of the pyridine series in solution. The bases thus obtained are exceedingly im- 

 pure, and contain aniline and some non-basic substances. It being probable, 

 that toluidine and even other members of the same series might be present, I 

 thought that as apparently insurmountable difficulties prevented their separation 

 from the chinoline series by means of oxalic acid, or similar methods, their 

 presence might nevertheless be made manifest through their products of decom- 

 position. With this view, I treated the mixed bases with nitrite of potash and 

 hydrochloric acid, in the manner indicated by Hunt,* and by this means effec- 

 tually decomposed all traces of the aniline group present. But the amount of 

 oil heavier than water containing the hydrates of phenyl and cresyl was too small 

 to allow of my further examining them. I propose, however, to return to the 

 subject at a future time. 



The acid fluid, after decantation from the heavy oil last alluded to, was then 

 placed in a retort, and a jet of steam sent through the tubulature to the bottom 

 of the liquid; by this means, many non-basic impurities were removed, and 

 amongst them a white crystalline solid distilled over with the steam, and which 

 eventually proved to be naphthaline. The acid fluid in the retort, after being 

 filtered through pulverized charcoal, to separate resinous matters not volatilized, 

 was treated with potash, to liberate the base, which was then separated by a tap 

 funnel, and completely dried by digestion with sticks of potash. It is proper to 



* Silliman's Journal 1849; Chem. Gaz., Jan. 1850; Gerhardt, Traite, tome 3 me , p. 83; 

 Hofmann, Quart. Jour. Chem. Soc. 



