Destructive Distillation of Animal Substances. 179 



during the process ; but so soon as I had ascertained that this 

 was not the case, it was 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 prolonged. 



The dark brown fluid which remained in the basins was 

 once more strained, in order to get rid of such resinous mat- 

 ters 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, potash, soda, and lime were indifferently 

 made use of: the latter answers extremely 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 sufficient 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 apparent, along with 

 another which can be compared to nothing but the smell of 

 stinking lobsters. At the first part of the distillation a trans- 

 parent 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 continuing the distil- 

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

 floating upon the concentrated fluid in the balloon, the quan- 

 tity of which is very variable, and depends on the distillation 

 of the crude bone-oil, having been continued 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 part of the investigation. 



To the product of the distillation sticks of caustic potash 

 were added ; and as these dissolved, the oily bases separated 

 from the fluid in a manner exactly 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 syphon, and more potash 

 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 



