Alcohol thermometer to give a background for reading the scale. The range of usefulness of the thermometer is set by the boiling point of the liquid used. In the case of the ethanol-filled thermometer, the upper limit for measurement is 78 °C (172.4 °F), which makes it useful for measuring daytime, nighttime and body temperatures, although not for anything much hotter than these. Ethanol-filled thermometers are used in preference to mercury for meteorological measurements of minimum temperatures and can be used down to −70 °C (-94 °F). The physical limitation of the ability of a thermometer to measure low temperature is the
Beckmann thermometer Beckmann thermometer A Beckmann thermometer is a device used to measure small differences of temperature, but not absolute temperature values. It was invented by Ernst Otto Beckmann (1853 – 1923), a German chemist, for his measurements of colligative properties in 1905. Today its use has largely been superseded by electronic thermometers. A Beckmann thermometer's length is usually 40 – 50 cm. The temperature scale typically covers about 5 °C and it is divided into hundredths of a degree. With a magnifier it is possible to estimate temperature changes to 0.001 °C. The peculiarity of Beckmann's thermometer design is a reservoir