In his interesting and informative book "Is That a Fact?," Joe Schwarcz avers that pigs do not sweat and the saying "sweating like a pig" originates in iron smelting. Oblong pieces of hot iron, with a fancied resemblance to a sow with piglets, cool in sand to the dew point of the surrounding air, and hence water condenses on the "pig." But this explanation, which the author had seen on the Internet, lacks a few caveats. It implies that molten iron, solidifying and cooling, anywhere, anytime, accretes liquid water, as if this were a special property of cooling iron. The true fact is that iron's thermophysical properties are not conducive to dew formation, and maximum dewfall is a fraction of a millimeter, it is difficult to envision a big, fat iron pig slathered in sweat after a hard night of cooling, even outside a smelter. Absent evidence to the contrary, "sweating like a pig" strikes the author as irony, meaning straining to do something to no effect.