Having thus vanished levity, and its upward motion, from all the boundaries of nature, we aver anew, that the elements of air and fire, which alone c… - Jean Rey

Almost all philosophers, ancient and modern, fearing an eternal confusion of the elements, were they all endowed with weight, conceived the two uppermost to be furnished with a certain levity, by means of which they bounded up on high, each to occupy its peculiar place, like as the two lower ones are pushed downwards by their own weight. But having clearly shewn in the last Essay, that levity is not necessary for that effect, weight alone being sufficient, I embrace the maxim, which they themselves have prudently laid down, that we should never multiply existences unnecessarily; assuming that God and Nature do nothing in vain, (which they also teach.) I think it would be otherwise were we to admit levity, since it is of no use.

[W]e must not only inquire whence these seven ounces are derived, but, moreover, whence that which has replaced the loss of weight, necessarily arising from the enlargement of volume of the tin, by its conversion into calx, and from the vapours and exhalations that have escaped.

Plants too ought to become heavy by death, the celestial heat being expelled: but the contrary is evident to all. As to the increased weight of animals by death, the true cause, far remote from that which increases the weight of lead when calcined, is this: in the living animal its natural heat subtilizes, dilates, and augments the dimensions of the humours, the flesh, and every thing in it capable of dilatation—but losing this heat by death, the whole on this becoming cold, contracts and diminishes, whence the increase of weight, as I have often said already. What is there like this in lead?