Storm glass

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The storm glass or chemical weather glass was an instrument claimed to help predict weather. It consists of a special liquid placed inside a sealed transparent glass. The state of crystallization within the liquid was believed to be related to the weather. The inventor is unknown but the device became popular in the 1860s after being promoted by Royal Navy Admiral Robert FitzRoy who claimed that "if fixed, undisturbed, in free air, not exposed to radiation, fire, or sun, but in the ordinary light of a well-ventilated room or outer air, the chemical mixture in a so-called storm-glass varies in character with the direction of the wind, not its force, specially (though it may so vary in appearance only) from another cause, electrical tension". The composition of the liquid in a storm glass varies but usually contains "camphor, nitrate of potassium and sal-ammoniac, dissolved by alcohol, with water and some air." These devices are now known to have little value in weather prediction but continue...

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