244 Dr. AV. lliimsay on Plcoline 



is not analogous to any known compound of platinum chloride 

 with ammonia. 



Oxidation of Picoline. — 4 ounces of picoline were oxidized 

 by Professor Dewar's process (Trans, Roy. Soc. Edinb. 1872, 

 pp. 189-196) with potassium permanganate. After the re- 

 duced manganese had been removed by filtration and the im- 

 oxidized picoline recovered by distillation, the liquid was 

 neutralized, boiled, and precipitated while boiling with excess 

 of silver nitrate. The extremely bulky curdy precipitate was 

 filtered through cloth, squeezed, and washed repeatedly with 

 boiling water. It was then again stirred up with water till 

 thoroughly disintegrated, and decomposed with sulphuretted 

 hydrogen, or with hydrochloric acid. After the silver sul- 

 phide or chloride had been filtered off, the liquid w^as concen- 

 trated to a comparatively small bulk ; on cooling, long white 

 crystals of dicarbopyridenic acid, C7 H5 NO4, filled the whole 

 vessel. After these crystals were removed, the mother-liquor 

 gave a second, but much smaller, crop on further evaporation ; 

 it was also collected, and the filtrate was set apart for further 

 investigation. 



The filtrate from the precipitate with silver nitrate con- 

 tained but a very small amount of organic substance. I suc- 

 ceeded in isolating a small amount of oxalic acid from it, by 

 precipitation with lead acetate. No organic acids, however, 

 crystallized out when it was evaporated to a small bulk and 

 mixed with sulphuric acid. 



When dicarbopyridenic acid deposits from an impure solu- 

 tion, it crystallizes in hair-like needles of great length, which 

 are anhydrous. This form, dissolved in hot water and re- 

 crystallized, deposits in plates resembling naphthaline, as re- 

 marked by Mr. Dewar. But these are not the only forms in 

 which it crystalizes. If the long hair-like crystals be allowed 

 to remain in Avater for some wrecks, their shape changes to 

 that of blunt prisms, apparently formed of a number of these 

 plates agglomerated together. These latter crystals contain 

 one molecule of water, as proved by the following esti- 

 mation : — 



0-3088 grm., after being heated to 100° for some hours, 

 lost 0-0293 grm., = 9-49 per cent. C7 H5 NO4 . H2O contains 

 9 '83 per cent, of w^ater. 



ISTone of the crystalline forms of this acid were sufficiently 

 well defined to allow of the determination of their crystallo- 

 graphic constants. The acid has a remarkably sweet taste, 

 but no smell. Its melting-point, when anhydrous, was 

 found, by repeated determinations, to be 237°*5. On crys- 



