But perhaps this discourse may seem to thee unprofitable, and superfluous, because this trial of metals is known all the world over: but for answer, I say that it is not superfluous, because many refiners erre, supposing that corporeal Lead together with the imperfect metals that are mixed with it, goes into the cuple, not being yet turned into Litharge, because corporeal Lead is again melted from thence; for whose sake this discourse is not properly ordained, as being those that operate out of use, and custom only without discretion; but rather for their sakes, who do incessantly seek after, and search into the secrets of nature, _viz._ seeking after that Philosophical tryal, which is known to few, by the help whereof more gold and silver is obtained than by the common way, but it is not to be discovered in this place; for all must not have the knowledge thereof; It is sufficient that I have demonstrated the possibility thereof. Yet know this, if thou knowest how to prepare Lead, Tin, Copper, and Iron, and to fit them for a radical union, _viz._ that aforesaid water of Saturn, so as they may endure the force of the fire together, thou mayst separate and attract gold, and silver from the aforesaid imperfect metals, and with gain leaving them in the cuple, or else you shall draw little or nothing from thence [_See Explicat. Mirac. Mundi._] And if you do intend to try them with Lead after the vulgar way, and bring them into dross, yet you do nothing, because tin and iron abounding with gold and silver, do not remain with the lead in a strong fire, but are lifted up like a skin or dross, by reason of their superfluous sulphur, swimming like fat upon water, without any separation, unless it be tin or iron, which got gold or silver from the mine in their first fusion. And by this means it falls out sometimes, that some may make a good proof, but out of ignorance, not knowing a reason of their operation, wherefore they cannot do the same again. For if Chymists, and Refiners did consider the matter more profoundly, enquiring the cause, wherefore lead being tryed, deprived of its silver, and melted in a cuple, should yet contain in it self silver, without doubt they would hit upon a good foundation; without which knowledge all their labour in imperfect metals would be in vain. And let this suffice concerning that Philosophical tryal, which is known to few; There is no need of speaking any thing of that vulgar, being every where known, of which _Lazarus Ercker_ wrote plainly and fully.