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XIX.—On Some New Bases of the Leucoline Series. By G. Carr Rosinson, 
F.R.S.E., Demonstrator of Chemistry, Public Health Laboratory, 
University of Edinburgh. 
(Read 1st July 1878.) 
Of the bases of the C,H.,_1,N series, obtained from coal-tar and from the 
“acid-tar ” from the distillation of shale, only three are known, viz., Leucoline, 
C,H,N ; Iridoline, C,,H,N ; and Cryptidine, C,,H,,N. These are isomeric with 
the bases obtained by the distillation of cinchonine with caustic potash, and are 
described by their discoverer, GREVILLE WILLIAMS, in “Trans. Royal Society, 
Edinburgh,” vol. xxi. The leucoline series of bases, at first thought to be identical 
with the cinchonine series, WILLIAMS has shown to be isomeric, but otherwise 
having important differences, these differences chiefly being apparent in their 
boiling points, their slight tendency to form crystallisable salts, and their 
reaction with iodide of amyl. 
The source of the leucoline bases of GREVILLE WILLIAMS was “ coal-oil of a 
very high boiling point, and a density greater than that of water ;” his process 
of separation was to treat the oil with sulphuric acid, and distil the acid liquid 
with lime ; that portion of the distillate which sinks in water is treated with 
nitrite of potash and hydrochloric acid to destroy phenols; the acid liquid is 
placed in an iron retort and a current of steam passed through it; the residue 
remaining in the retort, after being treated with caustic potash, is distilled, and 
the distillate, consisting of the mixed bases, purified by fractional distillation ; 
the bases were then identified by converting the fractions into platinum and 
other salts. Proceeding in this manner, GREVILLE WILLIAMS separated the 
three bases—leucoline, iridoline, and cryptidine ; the last, cryptidine, C,H,N, 
being found in his highest fraction, that boiling 270°-275° C., and from what 
I can learn from other authorities, the isolation of the higher members of this 
series has not been attempted. 
For the material on which I have worked, the results of which investigation 
T now lay before the Society, I am indebted to the kindness of Messrs 
GELLATLY and J. S. THomson, chemists to Young’s Paraffin Oil Company, West 
Calder, who have also kindly supplied me with the following account of the 
process of purification the bases went through before being sent to me :— 
“ Extraction and Purification of Bases from Acid Tar from Shale Oil. 
“Tn order to set free the bases and remove the colouring matter and foreign 
VOL, XXVIII. PART IL, ae 
