[CHAP. IV.]
Of the Volatile Alkali.
PROCESS I.
Volatile Alkalis rectified and depurated.
Mix together the Spirit, the Volatile Salt, the Phlegm, and the Oil, obtained from any substance whatever. Put the whole into a large wide-mouthed glass body, and thereto fit a head with a large beak. Set this alembic in a water-bath, lute on a receiver, and distil with a very gentle heat. There will ascend a Spirit, strongly impregnated with a Volatile Alkali, and a Volatile Salt in a concrete form, which must be kept by itself. Then increase your heat to the degree of boiling water; whereupon there will rise a second Volatile Spirit, somewhat more ponderous than the former, with a light Oil that will swim on its surface, and a little concrete Volatile Salt. Proceed till nothing more will rise with this degree of heat. Keep by itself what came over into the receiver. At the bottom of the cucurbit you will find a thick fetid Oil.
Into such another distilling vessel put the Spirit and Salt that rose first in this distillation, and distil them in the balneum mariæ with a heat still gentler than before. A whiter, purer, Volatile Salt will sublime. Continue the distillation till an aqueous moisture rise, which will begin to dissolve the Salt. At the bottom of the vessel will be left a phlegm, with a little Oil floating on it. Keep your Salt in a bottle well stopped.
OBSERVATIONS.
In the analysis of any substance that yields a Volatile Alkali, this Salt is generally found in the receiver, blended with the other principles of the mixt; which, ascending from the retort in the form of liquors and vapours, dissolve the Salt, or at least moisten it, and render it very impure. So that, if you desire to have it without any mixture, recourse must be had to a second distillation, in order to separate it from the heterogeneous matters with which it is confounded.
It is of consequence in this distillation to apply but a very weak degree of heat; because on that depends the success of the operation, insomuch that, the less heat you employ to sublime the Salt, the purer it will be. For, being far more volatile than any of the other principles with which it is mixed, it must evidently rise by itself, if no more heat be applied than is just necessary to elevate it; such a heat being much too weak to raise the Oil and phlegm with which it is blended.
Nevertheless, whatever care be taken to govern the heat, it is not possible to hinder this Volatile Salt from carrying up some portions of the principles mixed with it; those, to wit, with which it is most closely united, and to which it hath by that means communicated a share of its volatility. For this reason it requires a second rectification, which is performed in the same manner as the former. But, seeing it is more volatile and lighter after the first rectification than before, being thereby freed from part of the heterogeneous matters with which it was loaded, a still less degree of heat must be applied in this second rectification.