This indeed is wonderful, and stupendous, that a thing every where found most vile and base, should doe so great a miracle: I know not what moved me to write of it, knowing that I shall in this part offend not onely the wise by writing so openly, but also the ignorant detractors, and slanderers that will accuse me of falsity. And truly these considerations might justly have deterred me, but that I knew I might doe a good work, recalling many from their errors: For many are perswaded that there is no other dissolving _Menstruum_, besides the aforesaid corrosive spirits; but those are Chymists that are ignorant of Nature; yet the Philosophers with one consent say, that those corrosive destructive spirits make a fruitless solution of metals; for experience testifies, that the solutions made by the help of _aqua fortis_, and _regia_, and other spirits, colour the hands, being that which a true Philosophical solution doth not, and furthermore, testifies, that those, _viz._ which colour the hands, are not to be reckon’d among the true Philosophical solutions, but to be contemned as Malignant. Wherefore I was willing to write these things to instruct those that erre. Let no man therefore perswade himself, that a _Menstruum_ so vile and contemptible, is of less efficacy, than those corrosive spirits. I my self did once scarce believe, that so great Vertues could be in so most vile a _Menstruum_, until I had experience of the truth in good earnest. I could here add more things concerning the original of the universal _Menstruum_, which is so contemptible, which doth by its wonderful powers and vertues dissolve all metals, minerals and stones radically without any noise, unites and fixeth them; the solution whereof doth not colour the hand; the conjunction is inseparable, and the fixation incombustible; I say, I could add more things concerning it, but that divers inconveniences, which by this means I might incur, as also the envy and hatred of others do deter me. For although any one doth think to discover the possibility of Art, and Nature; yet few would be content therewith, being very desirous of all manner of revelation; and if we should not gratify them, we should forthwith incur their hatred and envy, who would without doubt judge otherwise of the matter, if they had but any experience of our labours. Be thou therefore (courteous Reader) contented with this discourse, that shews thee the possibility of Art and Nature; and diligently seek after it in the fear of God, and without doubt thy labour shall not be in vain. _Of the Building of the Furnaces._