DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 581 
generally stopped at the end of the second day, when a considerable quantity of 
the picoline still remained unchanged, and the contents of the flask had acquired 
the consistence of treacle. The flask was then broken, the sodium removed as 
completely as possible, and the whole, along with the pieces of broken glass, to 
which a considerable quantity of thick matter adhered, was thrown into water. 
When the oil had collected at the bottom, which generally required some hours, 
the pieces of glass were removed, the supernatant fluid decanted, and the oily 
base washed with water, so as to remove the soda and the greater portion of the 
unchanged picoline. Occasionally a somewhat different process was adopted; 
the cohobating tube being replaced by another bent at right angles, and the heat 
continued, so as to distil off and recover the dry picoline; but this was found 
less convenient, as the increased viscidity of the contents of the flask rendered its 
after-treatment more troublesome. The well-washed oil was introduced into a 
small retort, and heat applied. At first a watery fluid containing picoline came 
over, then dry picoline appeared, and subsequently an oil insoluble in water, 
began to distil; while a thermometer, placed in the tubulature of the retort, rose at 
first very rapidly, afterwards more slowly, until, towards the end of the distilla- 
tion, the temperature reached a point considerably beyond the range of the ther- 
mometer. Some crystals of carbonate of ammonia made their appearance in the 
neck of the retort ; traces of pyrrol could be distinguished, and a quantity of 
charcoal was left. These experiments rendered it sufficiently obvious that the 
new base possessed a boiling point so high, and so near its point of decomposition 
as to render necessary the utmost precautions for its purification. The first por- 
tion of the distillate which contained unchanged picoline was therefore rejected, 
and the remainder was heated in a retort immersed in the oil-bath to the boil- 
ing point of picoline, while a current of dry hydrogen was passed through it. 
At first a small quantity of picoline and some crystals of carbonate of ammonia 
made their appearance; and when these ceased to increase, the temperature of 
the bath was raised until it reached 380°, when the receiver was changed, and 
the heat maintained as steadily as possible between that point and 400°, the 
current of hydrogen being continued all the time. The base was thus made to 
evaporate at a temperature considerably under its boiling point, and was obtained 
in a much more satisfactory state, but even then it was not absolutely pure, as 
it still gave faint indications of pyrrol, although the quantity must have been 
excessively small; and though wholly soluble in acids, the solution retained a 
distinctly empyreumatic smell. The small scale on which it was necessary to 
experiment rendered it impossible to adopt any very efficient means of removing 
these impurities; but by a second rectification in the current of hydrogen, when 
the first portions were again rejected, a considerable improvement took place. 
Parapicoline is a pale yellow oil of the consistence of a fixed oil, which ac- 
quires a brown colour by exposure to the air. It is insoluble in water, although 
