DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 467 



dispensed with, and the fluid boiled down in porcelain or copper evaporating 

 basins, water being added, and the distillation continued until, by taking a small 

 quantity of the fluid and distilling off a few drops in a retort, they were found to 

 be free from pyrrol. Even this precaution soon became unnecessary, for a little 

 experience enabled me to know when the evaporation had been sufficiently pro- 

 longed. 



The dark-brown fluid which remained in the basins was once more strained, 

 in order to get rid of such resinous matters as might have separated during the 

 evaporation, and then distilled in a large glass balloon connected with a condenser, 

 after the acid had been previously supersaturated by a base. For this purpose, 

 potass, soda, and lime were indifferently made use of: the latter answers ex- 

 tremely well, but, owing to the large quantity of sulphate of lime separated, the 

 distillation requires to be carried on in the chloride of calcium or oil bath. When 

 the alkali is added in sufiicient quantity, an oil floats up to the surface of the 

 fluid, and a strong pungent odour is given off", in which that of ammonia is appa- 

 rent, along with another which can be compared to nothing but the smell of stink- 

 ing lobsters. At the first part of the distillation a transparent and colourless 

 watery fluid passed over, which contained the bases in solution ; but after this 

 had continued for some time, an oil made its appearance running in globules 

 down the tube of the condenser, and dissolving immediately in the fluid which 

 had already distilled. When the bases ceased to distil in quantity, the receiver 

 was changed, and a small quantity of oil heavier than water was obtained by con- 

 tinuing the distillation for some time. At the end of the process an oil remained 

 floating upon the concentrated fluid in the balloon, the quantity of which is very 

 variable, and depends on the distillation of the crude bone-oil, having been con- 

 tinued too long before changing the receiver. In fact, it contains some of the 

 bases of the less volatile oil, and will come to be considered in an after pai't of 

 the investigation. 



To the product of the distillation sticks of caustic potass were added, and, as 

 these dissolved, the oily bases separated from the fluid in a manner exactlj' similar 

 to that which was observed in the preparation of picoline, as detailed in the paper 

 to which reference has already been made. The alkaline solution was drawn off 

 by means of a siphon, and more potass added as long as water was separated. In 

 this way the greater part of the base was obtained, but a small quantity of the 

 most volatile of all still remains in the alkaline solution, and cannot be separated 

 except by the addition of a very large quantity of potass. It was, however, 

 readily obtained by distilling the fluid, and collecting only the flrst portion of 

 the product, from which it was separated by a comparatively small expenditure 

 of potass. The small quantity so obtained was preserved separately from the 

 large mass. 



VOL. XVI. PART IV. 6 D 



