impurity; then draw off the water gently in _Balneo_, or Sand, which again pour upon the remaining salt of Tartar, and again draw it off; this do so often as is needful, until all the water be consumed. Which being done, take out the salt, and weigh it, being first made red hot in the Fire, and thou shalt find it to be increased in weight, which increase came from the water, and not elsewhere. Note well that the cohobation of the water is to be reiterated often upon the salt of Tartar. Observe, that by this means, the water is convertible into salt by Art, _&c._ And if thou dost not believe the conversion of things material and corporeal, how wilt thou believe the conversion of things immaterial, as of the Sun, and Fire into a material fixed substance; of which thing, something shall be treated in our Treatise of _Aurum potabile_, and more at large afterwards in a Treatise _De Generatione Metallorum_, if God permit: For you must know that the circulation of the Elements, and things elementated, _viz._ how one is converted into another; and how they nourish and cherish one the other: as for example, the Earth yields Water, the Water Air, the Air Fire, and the Fire again Earth; which if it be pure, yields pure Earth. But that thou maist understand aright how any thing to be fixed, may be retained by another, by reason of affinity, observe the following example. The Husbandman casting seed into the Earth for to multiply, doth not choose any Earth, but that which is convenient for multiplication, _viz._ an Earth that is neither too dry, nor too moist; for the seed cast in sand cannot grow, but is lost: For whatsoever is to be preserved, is to be preserved by an equal temper; which, by how much it is more equal or like, so much the more perfect substance it doth produce. Humidity therefore being necessarily requisite for the growth of vegetables, without which, they can neither grow, nor multiply, but the seed being cast into moist sand, and the Rayes of the Sun acting upon the sand, and suddenly consuming the humidity thereof, whence follows the burning up of the seed in the dry sand, because there was no affinity betwixt the water, and sand; without which, the water could not be retained by the sand, and consequently, the seed deprived of its nutriment; it follows necessarily, that some _medium_ be required, or bond joining and binding the rain, and sand; _viz._ salt, by the help whereof, the rain water is retained by the sand, that it be not so easily consumed by the heat of the sun.