Precautions while using Laboratory Thermometers
Mercury thermometers, used in some science labs, require special safety precautions. Alcohol thermometers, though less dangerous, should still be handled carefully to avoid broken glass. Secondary thermometers are most widely used because of their convenience. Also, they are often much more sensitive than primary ones. For secondary thermometers knowledge of the measured property is not sufficient to allow direct calculation of temperature. They have to be calibrated against a primary thermometer at least at one temperature or at a number of fixed temperatures. Such fixed points, for example, triple points and superconducting transitions, occur reproducibly at the same temperature.