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DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 587 
was a mixture, it was shaken up with a small quantity of dilute acid, and the 
watery solution withdrawn. On the addition of caustic potash to this solution, 
an oil separated, which had the smell of picoline mixed with that of pyrrol. For 
the purpose of separating this picoline, the whole of the larger fractions were 
mixed and shaken up with a small quantity of very dilute sulphuric acid, and 
the solution, after being siphoned off, was replaced by another quantity, and 
this was repeated a third time. The oil was thus diminished by about a third 
of its bulk, and the whole of the picoline or other bases appearing to have been 
removed, it was carefully dried by means of sticks of caustic potash, and again 
rectified, when its boiling point was found to have been materially reduced. It 
began to boil at much the same temperature as the crude oil, but the largest 
fraction was now collected between 270° and 280°, while that which boiled above 
290° formed only a very small proportion of the whole; and after fifteen rectifi- 
cations, it was obtained in such a state that it distilled almost entirely between 
274° and 280°. In this condition it is a transparent and colourless oil, slowly 
acquiring a brown colour when exposed to air and light. It has a strong fetid 
smell, quite distinct from that of picoline, and a hot pungent taste. A piece of 
fir-wood, dipped in hydrochloric acid brought near its vapour, instantly acquires 
a fine red colour. When boiled with a dilute acid, it is immediately converted 
into a red resinous mass, which fills the fluid so completely, that the vessel con- 
taining it may be inverted without anything escaping. The fluid filtered from 
this substance is brown, and contains a small quantity of it in solution. After 
boiling for some time, so as to get rid of a peculiar smell which adhered to the 
fluid, and decompose the last traces of pyrrol, caustic potash was added, when 
the smell of ammonia, faintly contaminated with that of picoline, was evolved. 
The solution having been distilled, the ammonia was saturated with hydrochloric 
acid and bichloride of platinum added, when the platinochloride of ammonium 
was immediately precipitated, and the filtrate, on further evaporation, yielded 
an additional quantity of that salt, along with some indications of a more soluble 
platinum compound. For a long time I considered the oil prepared by the pro- 
cess now detailed to be pyrrol in a state of as great purity as it was possible to 
obtain it; and, as will be afterwards seen, it gave in different preparations, 
analytical results in perfect accordance with one another, and with its true 
formula ; but in the course of examining the effect of different reagents upon it, 
it was found that caustic potash exerted a very singular and perfectly unique 
action, disclosed the presence of a small quantity of some impurity, and afforded 
the means of removing it, when the properties of the pyrrol underwent a very 
remarkable change. When pyrrol is mixed with five or six times its weight of 
caustic potash in coarse powder, and heated over the lamp in a flask fitted with 
a long tube, it at first cohobates very freely ; but if the temperature be gradually 
raised, the fluid is found to distil up into the tube much less readily, and at 
VOL. XXI. PART IV. or 
