On the Tincture of Gold or True Potable Gold

pus, but not likewise in the solar rays.

He who wishes to test the truth in this way: let him expose to the sun’s rays a perfectly burnt cupel together with copper and lead, and place opposite it a concave mirror, so that it may be struck by the solar rays collected into a center, and thereby be heated: it is necessary, however, to hold the mirror in the hand continuously, so that you may turn or direct it according to the course of the sun; lest the cupel cool with the sun’s rays turned away, and the work be hindered: which, if it is duly observed, the work will be accomplished no less than in a furnace with the heat of a glowing fire.

It is necessary, however, to have a mirror at least two feet in diameter, and it must not be too deep, but have a depth of at least an 18th or 20th part of a globe, so that it may be able to cast its rays further; it must also be most exactly polished, by which it may most correctly collect the rays into a center or point. The preparation of these mirrors, however, does not belong to this place; but it will be given in the Fourth Part of our furnaces, where it will be taught not only how to form them from metals, but also from glass, and how they are to be polished and smoothed, and how they are to be used.)

This parenthesis and demonstration, which could have been omitted otherwise, has been appended so that it may appear how gold, having proceeded from the Sun and being endowed secretly with the powers and properties of the sun, is reducible by Chemical art into that which it was before its coagulation; namely, into a certain heating and life-giving spirit, its powers and gifts