
A NEW ORGANIC BASE FROM COAL-TAR. 125 
by exposure to the air; among these substances, of course, are all the basic 
compounds contained in the oil. The sulphuric acid which had been used for 
this purpose was neutralised by impure ammonia obtained by a single distillation 
of the watery fluid of the gas-works. On the addition of the ammonia there was 
no separation of any oil in quantity appreciable to the eye; but upon distillation, 
the bases, which had been dissolved in the fluid, passed over with the first por- 
tions of water, and collected in a separate layer in the receiver. This oil, when it 
came into my hands, possessed a very dark brown colour, a somewhat viscid con- 
sistence, and a peculiar pungent and disagreeable odour. It was heavier than 
water, a layer of which, containing a small proportion of oil in solution, floated 
on the surface. The examination of this oil proved it to consist, in addition to 
picoline, of a mixture of pyrrol, aniline, an oily base possessing the general pro- 
perties of leukol, and a thick heavy oil destitute of basic properties. 
In order to separate picoline, the oil, along with the water which floated on 
its surface, was introduced into a retort and carefully distilled. At first, water, 
accompanied by a little oil, passed over, and then an oil by itself, which dissolved 
completely in the watery fluid contained in the receiver. As the distillation pro- 
ceeded, another oil made its appearance, which collected in a layer on the surface 
of the fluid which had previously distilled. When about three-fourths of the oil 
had passed over, the process was stopped, by which means the oil, destitute of 
basic properties, which requires a very high temperature for its distillation, was 
left behind in the retort. The fluid in the receiver was now supersaturated with 
sulphuric acid diluted with water, care being taken to obtain a powerfully acid 
reaction. The peculiar odour which the fluid possessed, was by this process en- 
tirely changed, but not destroyed; and, on distillation, the water which passed 
over, carried with it all the pyrrol contained in the solution, while the other bases 
were retained by the sulphuric acid. Caustic potass was then added to the resi- 
due in the retort until an alkaline reaction was manifest, and it was again distil- 
led; the water which passed over carried with it the oily bases, partly dissolved, 
partly floating on the surface of the solution, exactly as in the first distillation. 
A few sticks of fused potass were introduced into-the product, and the whole was 
left in repose ; as the potass dissolved, the oil, which is entirely insoluble in solu- 
tions of the fixed alkalis, rose to the surface and there collected in the form of a 
pale yellow layer, still containing a considerable quantity of water, which may 
amount to 30 or 40 per cent. of the bulk of the oil. The oil was separated from 
the watery fluid by means of a pipette and pieces of fused potass added so long 
as they continued to become moist. The dry oil was then introduced into a retort 
and distilled. A transparent and colourless oil passed over, which was tested 
at intervals by allowing a drop of it to fall into a solution of chloride of lime. So 
soon as the reaction of aniline made its appearance the receiver was changed. 
The first portion was now picoline in a state approaching to purity; that which 
