Dr Anderson on the Properties of Picoline. 153 



hering pertinaciously to the hands and clothes. Its taste is 

 acrid and burning when concentrated ; but when very dilute, 

 as, for instance, when its vapour is sucked into the mouth, it 

 is powerfully bitter, as are also the solutions of its salts. It 

 is not changed by exposure to a cold of 0°. Picoline is ex- 

 tremely volatile, and evaporates rapidly in the air. It boils 

 at the temperature of 272°, and the thermometer remains 

 perfectly stationary during the whole period of the ebullition ; 

 it is therefore much more volatile than aniline, which, accord- 

 ing to Hoffman, boils at 359°. It may be preserved for a 

 long time in a bottle containing only a small quantity of it, 

 and which is frequently opened, without becoming manifestly 

 coloured ; whereas aniline becomes rapidly brown, and, in- 

 deed, cannot easily be obtained colourless, except by distil- 

 lation in a current of hydrogen. The specific gravity of pico- 

 line is less than that of water. I found it to be 0*955 at 50°, 

 while, according to Hoffman, that of aniline is 1-020 at 68°. 



Picoline mixes with water in all proportions, and forms a 

 transparent and colourless solution. It is insoluble, how- 

 ever, in solution of potass, as well as in most alkaline salts, 

 the addition of which causes its immediate separation from 

 the water. It dissolves also readily in alcohol, ether, py- 

 roxylic spirit, and the fixed and volatile oils. It is a power- 

 ful alkaline base : a rod dipped in hydrochloric acid, and held 

 over it, is immediately surrounded by a copious white cloud 

 of hydrochlorate of picoline. It restores the blue colour of 

 reddened litmus, but does not affect the colouring matter of 

 red cabbage. It does not coagulate the white of eggs as ani- 

 line does. 



The reactions which it produces with other substances are 

 also quite distinct from those presented by aniline. When 

 brought in contact with the solution of chloride of lime, it 

 does not produce, in the least degree, the violet colour which 

 is so characteristic of aniline ; on the contrary, the solution 

 remains perfectly colourless, unless, indeed, the picoline has 

 not been well separated from pyrrol ; in which case, a slight 

 brown makes its appearance, but no violet, Picoline is also 

 incapable of producing the yellow colour in fir wood and the 

 pith of the elder, which is so readily obtained with aniline. 



