Why in thermometers used mercury?
In the Middle Ages, people were interested in everyone – from philosophy to theology, from astronomy to medicine. In a painting to know the world around, tried to measure and the temperature of everything around. True, it was not so easy to choose the thermometric fluid. It should be answered by several criteria, one of which is the linear dependence of the volume of the liquid, that is, the length of the column with it, the temperature.
The first medical models of the thermometers proposed by another Galileem were made on the basis of water, but the dependence is very distorted in the region of about 4 ° C due to the characteristics of the chemical structure. This effect made errors in the coefficient of linear dependence and at temperatures is much higher than 4 ° C. In addition, water thermometers worked slowly, half an hour.
Alcohol-containing liquids turned out to be more successful. It is already difficult to establish who exactly the author of this idea. Only individual certificates about the experiments of Galilee and his students are preserved.
At about the same, in the XVI-XVII centuries, the alchemical teaching is actively developing, which was built on mercury-sulfur theory. So, despite the fact that alcohol containing thermometers are used and now, the attention of people switched to mercury – due to an amazing property: its volume when heated or cooling changes evenly, that is, in the first case, mercury is expanding and rises along the thermometer tube, and in the second – Sleeping.
Transition to mercury allowed to reduce temperature measurement time from half an hour to several minutes. In addition, mercury has a wide range of values available for measuring – from -37 ° C to +356 ° C, which also served in its favor.
The inventor of the first working mercury thermometer was the Dutch scientist Daniel Fahrenheit. In 1714, he collected the first instrument based on mercury, which possessed high measurement accuracy, and in 1724 he created his temperature scale, which is still used in the US. The first medical thermometer based on mercury created the English doctor Clifford Ollbat in 1866. This thermometer allowed to remove temperature readings in less than 5 minutes, while water and water-alcohol required for this more than 20.
Say that mercury is dangerous, not quite right. It, like any substance, can be in a solid, liquid or gaseous state. Metal mercury under normal conditions is a liquid that is not dangerous. But mercury, like any liquid, evaporates even at room temperature, and it is gaseous mercury and is danger. Evaporating and getting into the lungs, she remains there, poisoning the body: the mercury pairs are too heavy compared to air, and they will not succeed. And at least for harming the body, these couples must be inhaled for several months, to remove a broken thermometer better as soon as possible.
First of all, you must open in the window. Large mercury balls with a small tassel on a sheet of paper, following the example of a scoop, and small remove a one-time syringe or pipette. Throwing out into the garbage bucket they can not. Mercury balls, as well as parts of the thermometer, must be placed in a glass jar with cold water, close it and put it in a cool place. Water is needed to mercury not evaporated.
You can also sprinkle the scene of the sulfur powder, which is sold in business stores and stores for animals, or zinc, and then fastening the floor and rinse it with a mortar solution. If neither sulfur, no zinc or manganese at home, to prepare a hot soap soda solution, mixing 30 g of soda and 40 g of grated soap for one liter of water, and rinse the floor. The remaining couples will destroy during the air ventilation. Clothes, carpet and other things that were in contact with mercury will have to throw.
Then you need to call the regional department of regional Emergencies Ministry EMERCOM of Russia or to local civil defense and emergency situations that are obliged to pick up the jar with mercury balls and send to dispose of.
Such a serious attitude to the likelihood of getting harm caused a ban on mercury thermometers in the EU countries. Instead, there are liquid, made on the basis of tinted alcohol or Galinstan – alloy tin, India and Gallium, or electric thermometers. In 2020, it is planned to ban hydraisons with mercury and other devices, which contain this substance, and in Russia. In the meantime, as an option, you can use a thermometer with a protective polymer coating that will not give the glass to crash.