Barometric light
From Wikipedia, the free encyclopedia
Barometric light is a name for the phenomena where light is emitted by mercury in a barometer tube when shaken. The glow is an effect of the electricity generated by the friction of the mercury and the sides and air in the barometer tube. It is essentially the same effect as that in a modern neon lamp, though the effect occurs with gasses other than neon as well. It was first observed by Jean Picard (better known as an astronomer), and formed the subject of many experiments at the hands of Francis Hauksbee. The latter showed that the full vacuum was not essential to the phenomenon, for the same glow was apparent when mercury was shaken with air only partially rarefied, and that the effect could be produced without using the barometric tube.
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- This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
