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A short history of nearly everythingWe will travel great distances and pay small fortunes to see it in sunshine. And even though we know it is dangerous and drowns tens of thousands of people every year, we canБЂ™t wait to frolic in it. Because water is so ubiquitous we tend to overlook what an extraordinary substance it is. Almost nothing about it can be used to make reliable predictions about the properties of other liquids and vice versa. If you knew nothing of water and based your assumptions on the behavior of compounds most chemically akin to it-hydrogen selenide or hydrogen sulphide notably-you would expect it to boil at minus 135 degrees Fahrenheit and to be a gas at room temperature. Most liquids when chilled contract by about 10 percent. Water does too, but only down to a point. Once it is within whispering distance of freezing, it begins-perversely, beguilingly, extremely improbably-to expand. By the time it is solid, it is almost a tenth more voluminous than it was before. Because it expands, ice floats on water-БЂњan utterly bizarre property,БЂ«according to John Gribbin ...» |
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