The Storm Glass is a 18th century weather forecasting device, said to work as a “Chemical Barometer”. Inside a Storm Glass consists of a mix of Ethanol, Water, Potassium Nitrate, Ammonium Chloride and Camphor in a sealed clear tube. According to Fitzroy, to forecast the weather; patterns in the camphor crystals are interpreted, and meant to be used alongside other instruments such as the Barometer and Thermometer.
From the late 19th century onward these devices were considered to be simply crude thermometers and not worthy of further scientific investigation; However Fitzroy believed that these devices were also influenced by atmospheric electrical effects, and that they were more than mere crude thermometers.
The inventor of the Storm Glass is unknown, however the 19th century British Admiral Charles Fitzroy claimed that such devices were sold on Old London Bridge nearly a century before. All structures were removed from the Medieval London Bridge in 1762, Dating the Storm Glass to at least this period, if not earlier.