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DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 249 
has been made in the first part of this paper. As, however, I observed that a very 
powerful and pungent odour was evolved when the fluid began to boil, and the 
vapours presented the characteristic reaction of pyrrol in a very high degree, the 
head of the boiler was luted on, and the condenser attached, for the purpose of 
endeavouring to obtain that substance, which in my previous experiments I had 
not done. The fluid which distilled over carried with it a small quantity of oil, 
which, at the moment of distillation, was perfectly colourless, but soon acquired 
a reddish shade, and in the course of a few days became almost black. The 
greater part of this oil passed over with the first portion of water; but the last 
traces adhered with great obstinacy to the acid fluid, and could only be separated 
by very protracted distillation. The substance thus obtained proved to be a 
mixture of an oil insoluble in acids, and which appeared to be merely a small 
quantity of the crude oil, mechanically mixed with the fluid, and of a series of 
bases of very remarkable properties, and obviously related to one another, to 
which I shall afterwards refer under the provisional name of pyrrol bases. 
When these substances had entirely distilled, the fluid was allowed to cool, 
excess of slaked lime added, and the distillation again commenced, in order to 
obtain the bases which had been retained by the sulphuric acid. The separation of 
these was conducted in a manner in all respects similar to that employed in the 
former preparations, solid caustic potash being added in sufficient quantity to cause 
the separation of the bases held in solution in the water. The potash fluid, however, 
retained a certain proportion of ammonia, another gaseous base, and of the most 
volatile bases, which could be separated only by a very large excess of potash. 
The fluid was therefore distilled in glass vessels, and the product collected in a 
succession of three receivers, the first of which was kept cold by water, the second 
by a freezing mixture, and the third contained hydrochloric acid, for the purpose 
of condensing the gaseous products. The first receiver now contained the bases 
dissolved in a small quantity of water, from which they were readily separated 
by potash; the second receiver contained only a drop or two of liquid; but in the 
third the hydrochloric acid was rapidly saturated, and required repeated renewal 
during the progress of the distillation. 
The hydrochloric solution thus obtained contained a very large quantity of 
- chloride of ammonium, along with a small proportion of another base, in order to 
obtain which the fluid was slowly evaporated, allowed to cool at intervals, and 
the sal-ammoniac which deposited was separated by straining through cloth and 
expression. After the separation of several crops of crystals, a dark-brown 
mother liquor was left, which refused to crystallize by evaporation on the water- 
bath, but on cooling solidified into a mass of long foliated crystals, which soon 
deliquesced in moist air. These crystals still contained traces of sal-ammoniac, 
for the separation of which they were evaporated to complete dryness on the 
water-bath, and dissolved in the smallest possible quantity of absolute alcohol, 
