398 FAMILIAR COLLOQUIES.
straight, but to the centre ; and so when it came to the middle it would rest in the earth on the left hand, if the centre were at the left hand.
Cu. But what is H that makes a body heavy or light ? Al. That is a question fit for God to answer, why He made fire the lightest of all things, and air next to that ; the earth the heaviest, and water next to that. Cu. Why, then, do watery clouds hang in a lofty air? Al. Because by the attraction of the sun they conceive a fiery nature, as smoke being forced by a violent motion out of green wood. Cu. Why, then, do they sometimes fall with such a weight that they level moun- tains into, a plain ? Al. Concretion and density add a weight to them, and they may be imagined so to be borne up by the air under them, as a thin plate of iron is borne up upon the surface of the water. Cu, Do you think, then, that whatsoever has most of a fiery quality in it is lightest, and that which has most of an earthy quality heaviest 1 Al. You are right. Cu. But air is not all of a lightness, nor earth all of a heaviness, and it is the same as to water. Al. Nor is that strange, since those things you have mentioned are not pure elements, but tempered of various elements ; so that it is probable that earth is the lightest that has the most fire or air mixed with it, and that water heaviest that has earth, which is heaviest, mixed with it, as, I think, sea-water is, and that whereof salt is made. And, in like manner, that air that is nearest to water or earth is the heaviest, or, at least, it is certainly not so light as that which is farther from the earth.
Cu. Which has most of an earthy quality in it, a stone or lead 1 Al. A. stone: Cu. And yet lead is heavier than a stone in proportion. A I. (The density is the cause.) That proceeds from its solidity ; for a stone is more porous, and so contains more air in it than lead does. Hence it is that we see some sort of dry earth, which if you cast into water will swim and not sink; so we see whole fields floating, being borne up by hollow roots of reeds and other marshy herbs, interwoven one with another. Gu. Perhaps it is from this cause that a pumice- stone is so light. Al. Because it is full of pores, and very much burnt in the fire ; they are thrown out of burning places. Cu. Whence is it that cork is so light. Al. That has been answered already ; the spongy hollowness of it is the cause.
Cu. Which is heaviest, lead or gold 1 Al. Gold, in my opinion.
Cu. But yet gold seems to have more of a fiery nature than lead. Al. What, because, as Pindar says, it shines by night like fire 1 Cu. Yes. Al. But gold has the greater solidity. Cu. How is that found 1 Al. Goldsmiths will tell you that neither silver, lead, nor copper, nor any such kind of metal, can be hammered out so thin as gold can. And, for the same reason, philosophers gather that there is nothing more liquid than honey and oil ; that if any one spread this, or daub anything with it, it will spread the widest and be longest in drying of anything. Cu. But which is heaviest, oil or water 1 ? Al. If you speak of linseed-oil, I take oil to be the heaviest. Cu. Why, then, does oil swim upon water ? Al. The lightness is not the cause, but the fiery nature of oil, and a peculiar natiire in all fat things that is contrary to water; as it is in the herb that is called "A/3a7TTpc- Cu. Why, then, does not iron swim when it is red hot 1 Al. Because the heat is not a natural one, and therefore the sooner penetrates the
