Retorts made of the best earth do draw out the fire of Vitriol by
distillation after this manner following.
Common Vitriol is calcined in earthen pots unto a redness, and reduced
into a powder, it is put into an earthen Retort, and placed in a
Furnace, and a great vessel adjoyned to the neck of the Retort, which
is to receive the Spirits going forth; the fire is kindled by degrees,
and is gradually increased untill the Retort be brightly red hot,
in which degree of fire it is so long to be urged untill no white
Clouds or little vapoury Mists do any longer appear. This operation
is perfected in 24 hours space at the most. But if the Retort shall be
very large all the Oyl cannot be extracted in the space of 24 hours,
but will require a longer time for the operation, which experience
it self will determine: after all the Spirits are distilled off and
settled to the bottom of the Receiver, the clay luting which joyned the
Receiver to the neck of the Retort is to be mollified with a wet cloth
put round about it, and the Receiver taken off, and the spirits poured
out of it into a glass body well coated with Clay, the which (having
an Alembick put on) is to be set in sand, that the volatile Spirit may
slowly and gently be drawn off, and kept for its use afterwards to be
taught. Also afterwards the phlegm is to be drawn off, and reserved
for its own uses, because it hath its own peculiar virtues. At length
also the last spirit is to be received in a peculiar vessel, the which,
after that it hath ceased, and fiery drops do follow, the fire is (by
degrees) to be removed, and when the sand is cold, the gourd is to be
taken out, in which (the Alembick or head being taken away) thou shalt
find a fiery Oyl of a black or somewhat reddish colour, the which is
again to be rectified in an open fire in a Retort well coated, that it
may be rendred more fiery and clear.
By this oyl admirable things, and those not only profitable for
Physicians but also for Chymists, and other Artificers, are perfected
as we shall straitway see.
There are indeed other ways or means also by which this oyl is
attained, but this afore taught is the easiest of all, although it
require the more time. But if any one stand in need of a greater
quantity of the same, he may procure those greater Cans prepared of
the best Earth, they being so joyned to each other, that the uppermost
being placed on the fire, the rest might be placed without the fire, so
that the lowermost may receive the oyl going out by descent.
V. _A proof whether this Oyl of Vitriol be well prepared and
strong, and fit enough for that operation of which we here treat._
Let down a quill or some small piece of wood into the Oyl, the which,
when thou hast left in it for some small time, draw it out; if it shall
be burnt unto a Coal the oyl is well prepared, but if not, it is a
sign that somewhat of moisture is as yet therein, which is again to be
expelled by fire.