Consider discontinuing the use of thermometers containing mercury if it is used for cooking or is a clinical thermometer. Mercury is particularly harmful to fetuses, infants and children. Wilfrid Francis, Martin C. Peters, in Fuels and Fuel Technology (Second Edition), 1980. Historically, mercury thermometers have been used for nearly all temperature measurements because of their accuracy and low cost. The first thermometers manufactured contained water but the fact that water freezes at 32 degrees Fahrenheit led manufacturers to switch to mercury. The ethanol version is the most widely used due to the low cost and relatively low hazard posed by the liquid in case of breakage. Therefore, initially, thermometers defined temperatures. Thermocouples are among the most widely used industrial thermometers. The alternative to the mercury thermometer is the digital thermometer, which measures temperature by monitoring changes in electrical properties voltage and resistance of metals inside the device. What is the primary reason why liquid mercury (Hg) has been commonly used in thermometers for more than a century? Mercury is the only one in a liquid state at room temperature. Alcohol thermometers are considered much safer than the once popular mercury thermometers, but they are considered slightly less durable because the alcohol evaporates from the thermometer over time. If a mercury in glass thermometer is used, the observed firing temperature and the final temperature must be corrected as prescribed by the certificate issued with the instrument.. 2 Correction for the Cotton Thread. j) Mercury has a low latent heat for evaporation A: Mercury has been used in heat and pressure measuring instruments since the first intruments were made.. Metals are very good conducters of heat. There are a number of different model types, sizes, and specifications, but the general operating principle is about the same in all cases. Most metals are good conductors of heat and they are solids at room temperature. Mercury is opaque and bright, so the movement of mercury inside the capillary tube is easily visible. The first thermometers, however, weren’t thermos or heat measurers, but thermo-scopes, devices that merely signaled whether the temperature was high or low. However, it freezes at – 39 Celsius, so Mercury cannot be used below this temperature. The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. Mercury boils at 357°C, so, it can, therefore, be used to measure higher temperatures. Liquid thermometers can be limited by the type of liquid used. In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. Hence it is convenient to make marks on the thermometer surface. The EPA recommends the use of mercury-free thermometers but it does not endorse any specific brand and suggests choosing a thermometer that is easy to use and read. Electrical-resistance thermometers characteristically use platinum and, like thermistors, operate on the principle that electrical resistance varies with changes in temperature. Dangers of Mercury Mercury is a very dense element that is the only metal to exist as a liquid at room temperature. These non-mercury fever thermometers are just as good as mercury thermometers and much safer. For reprint rights: Times Syndication Service. Ethanol is cheaper and safer than mercury and can be used as low as -80˚C. g) Mercury is not an expensive metal. Metallic mercury is toxic, and also expensive. Mercury thermometers can be used to determine body, liquid, and vapor temperature. Mercury does not stick to the glass surface. 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