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 got 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. Horrman 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 which 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 all 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. Picoline forms a number of acid 
salts, in which respect it differs from aniline. Its salts are less readily decom- 
posed in the air than the corresponding aniline 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. 
