Fulcanelli ~ Dwellings of the Philosophers

[...] Let us leave aside these processes and tinctures. Above all, it is important to remember that the philosopher's stone appears in the shape of a crystalline, diaphanous body, red in mass, yellow after pulverization, dense and very fusible, although fixed at any temperature, and which its inner qualities render incisive, fiery, penetrating, irreducible and incalcinable. In addition, it is soluble in molten glass, but instantaneously volatilizes when it is projected onto molten metal.

[...]  The masters of the art teach us that the goal of their labors is triple.

What they seek to realize first is the universal Medicine or the actual philosopher's stone. Obtained in a saline form, whether multiplied or not, it can only be used for the healing of human illnesses, preservation of health, and growth of pants. Soluble in any alcoholic liquid, its solution takes the name of Aurum Potabile (potable gold, although it does not contain the least atom of gold) because it assumes a magnificent yellow color. Its healing value and the diversity of its use in therapeutics makes it a precious auxiliary in the treatment of grave and incurable ailments.

It has no action on metals, except on gold and silver, on which it fixes itself and to which it bestows its own properties, which, consequently, becomes of no use for transmutation. However, if the maximum number of its multiplication is exceeded, it changes form and instead of resuming its solid crystalline state when cooling down, it remains fluid like quicksilver and definitely not coagulable. It then shines in the darkness, with a soft, red, phosphorescent light, of a weaker brightness than that of a common night light. The universal Medicine has become the inextinguishable Light; the light giving product of those perpetual lamps, which certain authors have mentioned as having been found in some ancient sepulchers. Thus radiant and liquid, the philosopher's stone is not likely, in our opinion, to be pushed farther; desiring to amplify its igneous nature would seem dangerous to us; the least that could be feared would be to volatilize it and to lose the benefit of a considerable labor.

Finally, if we ferment the solid, universal Medicine with very pure gold or silver, through direct fusion, we obtain the Powder of Projection, the third form of the stone. It is a translucent mass, red or white according to the chosen metal, pulverizable, and appropriate only to metallic transmutation. Oriented, determined, and specific to the mineral kingdom, it is useless and without action in the two other kingdoms.