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Few of life鈥檚 anticlimaxes are more distressing than reaching into the fridge
at the end of a long day and taking out a warm beer. The answer, says B&H
Liquid Crystal Devices of London, is a beer mat (UK 2 311 371) that warns people
when lager is too warm and bitter too cold. The mat contains a layer of
thermochromic material. The thermochromic layer changes colour with temperature
so that the mat warns drinkers about the temperature of the beer.