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 fli-st 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, Avater, 

 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 oU 

 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 aU 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 flrst 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 oU was separated fi'om 

 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 



