From Peter Mahaffey
In his article on the unusual properties of water (6 February, p 32), Edwin Cartlidge failed to mention the weirdest property of all: the “Mpemba effect”. That is, if identical vessels of hot and cold water are placed in a freezer at the same time, the hot water will freeze first. This was first alluded to by Aristotle and then reported in the late 1960s as a result of observations by a young Tanzanian student. The findings were eventually published (Physics Education, vol 4, p 172), but the reason is still unexplained.
Bedford, UK
