Mercury-in-glass thermometer Mercury-in-glass thermometer The mercury-in-glass or mercury thermometer was invented by physicist Daniel Gabriel Fahrenheit in Amsterdam (1714). It consists of a bulb containing mercury attached to a glass tube of narrow diameter; the volume of mercury in the tube is much less than the volume in the bulb. The volume of mercury changes slightly with temperature; the small change in volume drives the narrow mercury column a relatively long way up the tube. The space above the mercury may be filled with nitrogen gas or it may be at less than atmospheric pressure, a partial vacuum. In order to calibrate
Candy thermometer Candy thermometer A candy thermometer, also known as a sugar thermometer, or jam thermometer is a cooking thermometer used to measure the temperature and therefore the "stage" of a cooking sugar solution. (See Candy making for a description of sugar stages.) These thermometers can also be used to measure hot oil for deep frying. There are several kinds of candy thermometers available. These include traditional liquid thermometers, coil spring "dial" thermometers and digital thermometers. The digital thermometers tend to read the temperature more quickly and accurately, and some models have an alarm when the thermometer hits a certain temperature. Many