For this relation I made only for to shew, how sometimes good things (though with intent to make them better) are made worse, and spoiled by those that do not make an exact search into nature and her power.
I hope this my admonition will not be taken ill, because my aim was not vain-glory, but only the good of my neighbour.
Now let us return again to Vitriol.
Of the sweet oyl of Vitriol.
The Ancients make mention of a sweet and green oyl of Vitriol, which doth cure the falling sickness, killeth worms, and hath other good qualities and vertues besides: and that the Oyl is to be distilled per descensum. To attain unto this oyl the later Physitians took great paines, but all in vain: because they did not understand at all the Ancients about the preparing of this oyl, but thought to get it by the force of fire, and so using violent distillation, they got no sweet oyl, but such as was very sowre and corrosive, which in taste, efficacy and vertue, was not comparable at all to the former.
However they ascribed unto it (though falsely) the same vertues, which the ancients (according to truth) did unto theirs. But daily experience sheweth, that the oyl of vitriol as it is found ordinarily, cureth no falling sickness, nor killeth worms, whereas this Philosophical doth it very quickly. Whence it appeareth, that the other is nothing like unto the true medicinal oyl of vitriol, neither is it to be compared to it.
I must confess indeed, that per descensum out of common vitriol, by the force of the fire, there may be got a greenish oyl, which yet is not better than the other, because it proveth as sharp in tast, and of as corroding a quality, as if it had been distilled through a Retort.
Those that found out this oyl, as Paracelsus, Basilius, and some few others, did always highly esteem it, and counted it one of the four main pillars of Physick. And Paracelsus saith expresly in his writings, that its viridity or greenness must not be taken away or marred (which indeed a very little heat can do) by the fire, for (saith he) if it be deprived of its greenness, it is deprived also of its efficacy and pleasant essence. Whence it may be perceived sufficiently, that this sweet green oyl is not to be made by the force of the fire as hitherto by many hath been attempted, but in vain.
And it is very probable, that the ancients, which did so highly praise the oyl of vitriol, happily knew nothing of this way of distilling, which is used by us now a days: for they only simply followed Nature, and had not so many subtle and curious inventions and ways of distilling.
But however it is certain, that such a sweet and green oyl cannot be made of vitriol by the force of the fire, but rather must be done by purification, after a singular way; for the Ancients many times understood purification for distillation: as it is evident, when they say, distill through a filtre, or through filtring paper: which by us is not accounted for distillation, but by them it was.