50 
DR. JOHN STENHOUSE ON THE NITROGENATED PRINCIPLES OF 
potash solution and floated on its surface. The lye was then slowly run off by open- 
ing the bottom of the funnel, and when the whole of it was removed the escape of 
the bases was prevented by again closing the neck of the funnel. This operation 
was repeated till the whole of the ammonia was removed. A quantity of the bases 
remained dissolved in the alkaline lye, occasioning a loss, which however was un- 
avoidable. The next step was to free the bases from the water they had absorbed, 
and which appeared to be nearly equal to that of their own bulk. The water was 
pretty readily removed by agitating the bases with bits of fused potash, so long as 
the alkali appeared to be in the least degree moistened. In order to ensure their 
being perfectly anhydrous, the bases were treated with successive quantities of fresh 
potash, and were kept in contact with the last portion for nearly a week. The clear 
liquid was then poured otf from the potash into a small glass retort and cautiously 
rectified. The first two-thirds of the liquid which came over was a colourless trans- 
parent oil. The last portions, which distilled at a much higher temperature, had a 
slightly yellow colour, which increased in depth towards the close of the distillation. 
The colourless and the coloured portions were therefore collected separately. By 
repeated rectifications, however, the last portions of the bases were freed from the 
resinous matter they contained, and rendered as transparent and colourless as the 
first portion. As it was plain from the great variation in their boiling-points that 
the liquids were not homogeneous but consisted of a mixture of bases, many attempts 
were made to obtain them in a separate state by means of fractionated distillation. 
A thermometer was therefore inserted into the mixture of the bases by means of a 
perforated cork passed through the tubes of the retort. The mixture began to boil 
at 108° C., when a very small portion of a limpid colourless oil, which was collected 
separately, distilled over. The thermometer rapidly rose to 120° C., and from that to 
130°, at both of which points small portions of oil were also collected. The boiling- 
point remained stationary for a considerable time between 150° and 155° C., when a 
considerable quantity of the oil distilled over, and a second large quantity also came 
over between 160° and 165° C. The boiling-points of the last portions of the bases 
ranged between 165° C. and 220° C. The products of these different distillations were 
again repeatedly rectified, and by this means bases were obtained corresponding 
more closely with those points at which the thermometer remained longest during 
the first distillation. Though these various bases differed, as we have just seen, so 
considerably in their boiling-points, they still exhibited great similarity of character. 
Thus they formed transparent colourless oils which refracted the light very strongly. 
They were all lighter than water, and possessed the peculiar, pungent, slightly 
aromatic smell, so characteristic of this class of compounds. When brought in con- 
tact with the hands or with clothes, their odour was very persistent. The smell of 
the more volatile bases was, as might have been expected, the most pungent. Their 
taste was hot, and when diluted not disagreeable, reminding one of oil of peppermint. 
The bases which distilled over at low temperatures were tolerably soluble in water. 
