1880.] 



Studies on the Chinoline Series. 



167 



Leucolinic acid does not decompose in glycerine before a temperature 

 of 205° is reached ; the general decompositions of this acid are clearly 

 identical with that of the isomeric acid obtained from the tar base, 

 and prove conclusively that both bases are intimately related to the 

 aromatic series. 



Nature of Tar Leucoline. 



According to the researches of Greville Williams the leucoline of tar 

 is distinguished from the corresponding cinchona base by its giving 

 an oily chromate, which in his hands never crystallised. 



The leucoline used in my experiments can be shown to be a mixture 

 of at least two isomeric bases, one of which yields a crystalline chro- 

 mate, which is not however identical with the chromate of the alkaloid 

 base. 



The portion boiling between 210° and 220° gave the largest yield of 

 the crystalline chromate. 



In no case did the mixture of the base with excess of chromic acid 

 give any crystals until it had stood for several days. 



After separating the crystals the free base was obtained by distilla- 

 tion with caustic potash, and gave immediately a well crystallised salt 

 on the addition of a little chromic acid. 



The base separated from the uncrystallisable chromate seemed to 

 boil on the whole at a lower temperature. 



Analysis of the crystalline chromate obtained from tar leucoline : — 



I. II. 



Weight of chromate taken 03285 0*3425 



Carbonic acid produced 0*5485 .... 0*573 



Water obtained 0-1030 .... 0\L12 



Calculated in percentages- 



I. II. Theory. 



Carbon 45*5 .... 54*6 .... 45*34 



Hydrogen 3*48 .... 3*62 .... 3*35 



Chromic oxide . . — .... — .... 31'99 



0*223 of the chromate gave 0*0715 chromic oxide, or 32*07 per 

 cent.; and 0*7915 of chromate from another sample gave on ignition 

 0*260 chromic oxide, or 32*8 per cent. These analyses leave no doubt 

 as to the substance being a pure variety of leucoline. 



That there are at least two distinct bases in tar may be proved in 

 other ways. 



If leucoline is digested in the water-bath for several days with a 

 large excess of chloride of ethyl, only one of the bases seems to com- 



VOL. XXX. N 



