Aristotle · a new plain-English translation from the original language
1| Why does every lake, if it is fresh, both wash and cleanse clothes? For the sweet washes, while the bitter cleanses, and it is not possible to have both at once. Or is it not by being bitter that anything cleanses, but rather stickiness that is what cleanses? That is why the extremities of animals and whatever is mucous are of this kind, so that even among bitter things, those that share in this stickiness cleanse. Now in this particular lake it happens that, of its natron-like power, the bitter part has been burned away, while the fatty and sticky part remains. By this, then, it cleanses, and it washes by means of its fresh water. Why does the calm part of the sea appear white, while the surging part appears black? Is it because what is less clearly seen appears darker? And what is in motion is seen less clearly than what is at rest. Or is it because what lets light show through appears white, and what does not appears black? And what is in motion lets light show through less. BOOK 24. PROBLEMS CONCERNING HOT WATERS. Why is hot water, if people have been anointed with oil, less hot when poured over them, even though the oil itself is hot? Is it because the oil, by smoothing the skin, makes it slippery, so that the water penetrates less? Why does the water in wells become hot after midday in summer? Is it because by that time the heat has already gained mastery over the air? For before midday the heat is still dissolving and checking the cold; it has not yet, at the same moment, both ceased and gained mastery, but only once time has passed.
2| Why does water, though sometimes becoming hotter than flame, not burn wood, whereas flame does burn it? Is it because flame is fine-particled, and so is the breath that comes from it, while water is coarse-particled, so that it does not penetrate in? Flame, and what comes off burning coals, penetrates because of its fineness and dissolves the wood. Why does boiling water not melt things, while the stomach does? Is it because the heat in the stomach enters because of its fineness, while water does not enter because of its thickness? Or is it because moisture in general prevents things from melting? For nothing melts while in a liquid. But in the stomach, the moisture, as it withdraws down into the bladder, dissolves things in this way. Why does the bottom of a vessel not burn while water is in it and boiling — indeed people can carry it while holding it by the bottom — but once the water is removed, it does burn? Is it because the heat generated at the bottom is quenched by the water? That is also why things that are meltable do not melt, unless a shock strikes them.
3| Why does water not boil over in winter in the same way as in summer, not only when it is heated to the same degree, but even when it is hotter, and heated more, and to an equal or greater degree still? Is it because boiling-over is the rising up of bubbles? Now the water itself is heated then no less than it would be apart from the cold, but the bubbles cannot rise in the same way, because the surrounding air is cold; rather, being compressed by the cold, they rise smaller in size, and, cut off by the air, they quickly collapse, so that they become fewer both in bulk and in number in winter, and the opposite happens in summer. Boiling-over occurs because of the abundance and size of the foam. Why does hot water wrinkle the skin, while fire, though hot, does not? Is it because fire produces breath, so that it swells the skin? For the skin is stretched taut, and a wrinkle is a folding. Why are the bottoms of vessels, while the water is being heated, hotter as long as the water is still cold? Is it because, while the water is still cold, the heat is shut in and turns back inward, being prevented from going out, but once the water inside has been thoroughly heated, it no longer holds it in, but lets it pass through, and as the fire becomes less, the bottom becomes colder — just as with bathhouses? For these too are hotter in winter than in summer, because the heat is shut in more in winter than in summer, since the surrounding air is cold.
4| Why does boiling water not spatter out, while pea soup and lentil soup do? And yet water is lighter than these, and light things are more easily thrown far. Silver does the same thing, too, when it is being refined; that is why the men who do the skimming in the silver-refinery profit by it, for by skimming together what is scattered about they collect the residue. Is it because what produces the spattering-out is the heat evaporating and forcing out whatever resists its motion according to its nature? Water, then, because of its lightness and fineness, does not force its way out violently, so that a large amount of heat does not gather in it, but before it can be massed together, whatever heat has just arrived breaks through and escapes. But things that have body in themselves, such as gruels or silver, having much of the bodily element by reason of their weight, and pushing back against the heat because it forces its way out violently, are flung off in globules wherever the heat manages to prevail; for it does not pass through, because of their density, but is held back until it is thrown off by the heat flowing in afterward. And what occurs is a blow, not a push, because the heat travels quickly from below upward.
5| Why do things soaked in hot water for a short time swell up, while things soaked for a long time collapse and become wrinkled? Is it because heat turns what is congealed into liquid, and liquid into vapor, and it rarefies what is dense? So the heat, warming the congealed matter at first, makes it more liquid, and by turning the liquid into vapor and dispersing it, it makes the bulk swell. But when the surrounding heat acts more strongly, it rarefies further, so that the vapor breathes out, and the liquid, drying up, makes the bulk collapse. As things collapse, the surrounding skin of everything wrinkles. And wherever this happens unevenly, that is where it becomes wrinkled. Why do stones form more from hot water than from cold? Is it that a stone forms by the failing of moisture, and moisture fails more under heat than under cold, so that petrifaction occurs on account of the heat — just as Empedocles too says that rocks and stones and hot springs come to be? Or does heat itself petrify, and things are also turned to stone by cold, because the excess of frost, using up the moisture, hardens them? This is clear, then, from the case of excess, and so also in the simple case. Why, when someone holds a foot in hot water, does it seem less hot while it stays still, but hotter once it is moved? Is it as with the body too — when someone runs in a breeze, the air standing in front of him is always cooler, but as he presses further into it he perceives it more?
6| Why do hot things cool faster in the sun than in the shade? Is it because the lesser heat is destroyed by the greater? Or is it that in the shade the cold standing around presses on the heat within and does not let it go out — which is just what the cold does to the dying when it pours in on them: it shuts the heat in and prevents it from leaving; and in general, in winter, the inner parts of everything turn out hotter. But in the sun, since nothing blocks it, the heat is carried off and departs faster. Why is water warmed by the sun for bathing not healthier? Is it because it cools again, and further because it makes the body shiver? Or does it do this too, but even if one bathes in it often, it is still unwholesome? For heat in general is concocting and drying, while cold is astringent, so that both do some good. That is why both cold water and water heated by fire are useful for bathing; but water heated by the sun, on account of the weakness of its heat, does neither of these, but rather moistens, like the light of the moon.
7| Why is water heated by the sun not good? Is it because things that are cooling make one shiver? Why are the hot springs at Magnesia and at Atarneus drinkable? Is it because a greater quantity of water flows in upon the hot water as it flows away, and its saltiness disappears while its heat remains? Why did the hot springs at Magnesia stop being hot, while the water remained salty? Is it that a greater quantity of foreign cold water was at the same time poured onto the springs, and quenched the heat within? And the earth was salty but not hot, on account of the quantity of water pouring in. So something similar happened as with water filtered through ash: for this too, being filtered through heat, cools that heat down, and itself becomes cold, and is salty and bitter on account of the ash. But since the water flowing in was foreign, for a different reason the heat present in the earth prevailed over the coldness of the water, because of its small quantity, and the springs became hot again. Why are hot waters generally salty? Is it because most of them are filtered through earth that is alum-like — their smell shows this — and burnt? And the ash of everything is salty and smells of sulfur. That is why it burns things through, just as lightning does. So many hot springs arise from the strike of lightning.