130 DR ANDERSON ON THE CONSTITUTION AND PROPERTIES OF PICOLINE, 



picoline must have been present along with aniline and chinoline in the sub- 

 stance which he examined. He mentions, especially, that his aniline, as obtained 

 by distillation only, possessed a peculiar pungent and disagreeable odour, which 

 was wot rid of only by several successive crystallizations of its oxalate from 

 alcohol, and that the impure aniline has a specific gravity less than that of 

 water. He observes, also, that the quantity of the substance present must have 

 been excessively minute, as it did not affect the results of the analysis, a pheno- 

 menon, the cause of which is sufficiently explained by the identity in constitution 

 of the two substances. Hoffman did not obtain picoline in the separate state, 

 simply because the bases employed by him were obtained from the less volatile 

 portions of coal-tar, which necessarily contain it only in minute proportion. 



Combinations of Picoline. 



Picoline forms a series of compounds which are generally closely analogous 

 to those of aniline, but present in a less marked degree the regularity and facility 

 of crystallization Avhich are so characteristic of the salts of the latter base. It 

 forms, however, with the greater number of acids, salts which can be obtained in 

 a crystalline form. These are aU highly soluble in water, and some of them are 

 even deliquescent ; they are also for the most part readily soluble in alchol even 

 in the cold. They are most readily obtained by evaporating their aqueous solu- 

 tions at 212°, and not by adding an acid to the etherial solution of the base ; as in 

 the latter case the presence of even a minute proportion of water causes them to 

 precipitate in the form of a semifluid mass. Picohne forms a number of acid 

 salts, in which respect it differs from anUine. Its salts are less readUy decom- 

 posed in the air than the corresponding anUine compounds, but they do event- 

 ually become brown, although without presenting any of the rose red colour 

 which the latter salts assume. 



Sulphate of Picoline. — I obtained this salt by supersaturating sulphuric acid 

 with picoline. The solution obtained was perfectly colourless, and when evapo- 

 rated in the water-bath, it evolved picoline in abundance, and formed a thick 

 oily fluid, which, on cooling, concreted into a tough mass of transparent and 

 colourless crystals, apparently of a tabular form. Exposed to the air, it deli- 

 quesces rapidly into a transparent and colourless oil, which, after a time, acquires 

 a slight brownish colour. It is insoluble in ether, but readily in alcohol, both hot 

 and cold. It is not deposited in crystals by allowing the hot alcoholic solution to 

 cool. I analysed this salt by evaporating to dryness in the water-bath, in a 

 weighed platinum crucible, and allowing it to cool under an exsiccator. It was 

 then rapidly weighed, dissolved in water, and precipitated by chloride of barium : — 



4-364 grains of sulphate of picoline gave 



5-230 ... sulphate of baryta = 41-20 per cent, of anhydrous sulphuric acid. 



