The liquid which is filled inside the bulb of thermometer is called thermometric liquid. Specially, mercury and alcohol are used as thermometric liquid.
In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. Mercury thermometers can be used to determine body, liquid, and vapor temperature.
Mercury is the only one in liquid state at room temperature. It's used in thermometers because it has high coefficient of expansion. Hence, the slightest change in temperature is notable when it's used in a thermometer.The small silvery ball in a mercury thermometer can be dangerous if the glass breaks and the mercury is not cleaned up properly. The mercury will evaporate and can contaminate the surrounding air and become toxic to humans and wildlife. Each thermometer contains about . 5-1.5 grams of mercury.Mercury is the only metal that is in liquid state at room temperature. It is used in thermometers because it has a high coefficient of expansion which makes it easy to move in the thermometers as per the temperatures.
Mercury readily turns into vapour at room temperature and when inhaled attacks the nervous system. The glass thermometer that we have been putting in our mouths for so many years contains the most lethal of ingredients that can pose serious health problems if accidentally spilt.Mercury is the only one in liquid state at room temperature. It's used in thermometers because it has high coefficient of expansion. Hence, the slightest change in temperature is notable when it's used in a thermometer. It also has a high boiling point which makes it very suitable to measure higher temperatures.