Thermometer:

Standard laboratory thermometer

The standard laboratory thermometer is filled with a fluid which expands in a predictable way for each degree centigrade it absorbs heat. Although old thermometers were used with Mercury, due to safety and environmental issues, they have been replaced by other fluids.

The typical laboratory thermometer has a range of -20°C to 120°C, which is sufficient for undergraduate teaching labs. Many of them are marked with both Fahrenheit and Celsius scales.

Note that the thermometer shown in the picture is an immersion thermometer, and the red bulb on the bottom should be completely surrounded by the fluid when being used to measure temperature. It should also not be in contact with the walls of a vessel, like the bottom of a beaker that is being heated.