Who invented mercury? Thermometer is a device for measuring air temperature. Types of temperature scales

He created something like a thermobaroscope (thermoscope). Galileo was studying at this time Heron of Alexandria, who had already described a similar device, but not for measuring degrees of heat, but for raising water by heating. The thermoscope was a small glass ball with a glass tube soldered to it. The ball was slightly heated and the end of the tube was lowered into a vessel with water. After some time, the air in the ball cooled, its pressure decreased and the water, under the influence of atmospheric pressure, rose up in the tube to a certain height. Subsequently, with warming, the air pressure in the ball increased and the water level in the tube decreased as it cooled, but the water in it rose. Using a thermoscope, it was possible to judge only the change in the degree of heating of the body: it did not show numerical temperature values, since it did not have a scale. In addition, the water level in the tube depended not only on temperature, but also on atmospheric pressure. In 1657, Galileo's thermoscope was improved by Florentine scientists. They equipped the device with a bead scale and pumped out the air from the reservoir (ball) and tube. This made it possible not only to qualitatively, but also quantitatively compare body temperatures. Subsequently, the thermoscope was changed: it was turned upside down, and instead of water, alcohol was poured into the tube and the vessel was removed. The operation of this device was based on the expansion of measures; the temperatures of the hottest summer and coldest winter days were taken as “constant” points. The invention of the thermometer is also attributed to Lord Bacon, Robert Fludd, Sanctorius, Scarpi, Cornelius Drebbel ( Cornelius Drebbel), Porte and Salomon de Caus, who wrote later and partly had personal relations with Galileo. All these thermometers were air thermometers and consisted of a vessel with a tube containing air separated from the atmosphere by a column of water; they changed their readings both from changes in temperature and from changes in atmospheric pressure.

Mercury medical thermometer

Thermometers with liquid are described for the first time in the city "Saggi di naturale esperienze fatte nell'Accademia del Cimento", where they are spoken of as objects that have long been made by skilled artisans, called "Confia", who heat the glass on the blown fire of a lamp and make It makes amazing and very delicate products. At first these thermometers were filled with water, and they burst when it froze; The use of wine alcohol for this purpose began in 1654 at the thought of the Grand Duke of Tuscany Ferdinand II. The Florentine thermometers are not only depicted in the Saggi, but have been preserved in several copies to this day in the Galilean Museum, in Florence; their preparation is described in detail.

First, the master had to make divisions on the tube, taking into account its relative sizes and the dimensions of the ball: the divisions were applied with molten enamel onto the tube heated in a lamp, every tenth was indicated by a white dot, and the others by black. They usually made 50 divisions in such a way that when the snow melts, the alcohol does not fall below 10, and in the sun does not rise above 40. Good craftsmen made such thermometers so successfully that they all showed the same temperature value under the same conditions, but this was not the case could be achieved if the tube was divided into 100 or 300 parts in order to obtain greater accuracy. The thermometers were filled by heating the ball and lowering the end of the tube into alcohol; the filling was completed using a glass funnel with a thin end that fit freely into a fairly wide tube. After adjusting the amount of liquid, the opening of the tube was sealed with sealing wax, called "sealant". From this it is clear that these thermometers were large and could be used to determine air temperature, but they were still inconvenient for other, more diverse experiments, and the degrees of different thermometers were not comparable with each other.

The Swedish physicist Celsius finally established both constant points, melting ice and boiling water, in 1742, but initially he put 0° at the boiling point, and 100° at the freezing point, and adopted the reverse designation only on the advice of M. Störmer. Surviving examples of Fahrenheit thermometers are distinguished by their meticulous execution. However, the “inverted” scale turned out to be more convenient, on which the melting temperature of ice was designated 0 C, and the boiling point 100 C. Such a thermometer was first used by Swedish scientists, botanist K. Linnaeus and astronomer M. Stremer. This thermometer is widely used.

For information on removing spilled mercury from a broken thermometer, see the article Demercurization

Mechanical thermometers

Mechanical thermometer

Window mechanical thermometer

This type of thermometer operates on the same principle as liquid thermometers, but a metal spiral or bimetallic tape is usually used as a sensor.

Electric thermometers

Medical electric thermometer

The operating principle of electric thermometers is based on the change in conductor resistance when the ambient temperature changes.

The wider range of electrical thermometers are based on thermocouples (contact between metals of different electronegativity creates a temperature-dependent contact potential difference).

Home weather station

The most accurate and stable over time are resistance thermometers based on platinum wire or platinum coating on ceramics. The most widely used are PT100 (resistance at 0 °C - 100Ω) PT1000 (resistance at 0 °C - 1000Ω) (IEC751). The dependence on temperature is almost linear and obeys a quadratic law at positive temperatures and a fourth-degree equation at negative temperatures (the corresponding constants are very small, and to a first approximation this dependence can be considered linear). Temperature range −200 - +850 °C.

Hence, the resistance at T°C, resistance at 0 °C, and constants (for platinum resistance) -

Optical thermometers

Optical thermometers allow you to record temperature by changing the luminosity level, spectrum and other parameters (see Fiber Optic Temperature Measurement) as the temperature changes. For example, infrared body temperature meters.

Infrared thermometers

An infrared thermometer allows you to measure temperature without direct contact with a person. In some countries, there has long been a tendency to abandon mercury thermometers in favor of infrared ones, not only in medical institutions, but also at the household level.

An infrared thermometer has a number of undeniable advantages, namely:

safety of use (even with serious mechanical damage there is no threat to health)
higher measurement accuracy
minimum procedure time (measurement is carried out within 0.5 seconds)
possibility of group data collection

Technical thermometers

Technical liquid thermometers are used at enterprises in agriculture, petrochemical, chemical, mining and metallurgical industries, mechanical engineering, housing and communal services, transport, construction, medicine, in short, in all spheres of life.

There are the following types of technical thermometers:

technical liquid thermometers TTZh-M;
bimetallic thermometers TB, TBT, TBI;
agricultural thermometers TS-7-M1;
maximum thermometers SP-83 M;
low-degree thermometers for special chambers SP-100;
special vibration-resistant thermometers SP-V;
mercury electrocontact thermometers TPK;
laboratory thermometers TLS;
thermometers for petroleum products TN;
thermometers for testing petroleum products TIN1, TIN2, TIN3, TIN4.

Mercury medical thermometer

Electronic thermometers

Medical electronic thermometer

The operating principle of electronic thermometers is based on the change in conductor resistance when the ambient temperature changes.

The wider range of electronic thermometers are based on thermocouples (contact between metals with different electronegativity creates a contact potential difference that depends on temperature).

Home weather station

R T = R 0 [ 1 + A T + B T 2 + C T 3 (T − 100) ] (− 200 ∘ C< T < 0 ∘ C) , {\displaystyle R_{T}=R_{0}\left\;(-200\;{}^{\circ }\mathrm {C} R T = R 0 [ 1 + A T + B T 2 ] (0 ∘ C ≤ T< 850 ∘ C) . {\displaystyle R_{T}=R_{0}\left\;(0\;{}^{\circ }\mathrm {C} \leq T<850\;{}^{\circ }\mathrm {C}).}

From here, R T (\displaystyle R_(T)) resistance at T°C, R 0 (\displaystyle R_(0)) resistance at 0 °C, and constants (for platinum resistance) -

A = 3.9083 × 10 − 3 ∘ C − 1 (\displaystyle A=3.9083\times 10^(-3)\;()^(\circ )\mathrm (C) ^(-1)) B = − 5.775 × 10 − 7 ∘ C − 2 (\displaystyle B=-5.775\times 10^(-7)\;()^(\circ )\mathrm (C) ^(-2)) C = − 4.183 × 10 − 12 ∘ C − 4 . (\displaystyle C=-4.183\times 10^(-12)\;()^(\circ )\mathrm (C) ^(-4.)

Optical thermometers

Infrared thermometers

An infrared thermometer allows you to measure temperature without direct contact with a person. In some countries, there has long been a tendency to abandon mercury thermometers in favor of infrared thermometers, not only in medical institutions, but also at the household level.

Technical thermometers

Technical thermometers are used at enterprises in agriculture, petrochemical, chemical, mining and metallurgical industries, mechanical engineering, housing and communal services, transport, construction, medicine, in a word, in all spheres of life.

Santorio was not only a doctor, but also an anatomist and physiologist. He worked in Poland, Hungary and Croatia, actively studied the breathing process, “invisible evaporations” from the surface of the skin, and conducted research in the field of human metabolism. Santorio conducted experiments on himself and, studying the characteristics of the human body, created many measuring instruments - a device for measuring the force of pulsation of arteries, scales for monitoring changes in human weight, and the first mercury thermometer.

Three inventors

It is quite difficult to say today who exactly created the thermometer. The invention of the thermometer is attributed to many scientists at once - Galileo, Santorio, Lord Bacon, Robert Fludd, Scarpi, Cornelius Drebbel, Porte and Salomon de Caus. This is due to the fact that many scientists simultaneously worked on creating a device that would help measure the temperature of air, soil, water, and humans.

There is no description of this device in Galileo's own writings, but his students testified that in 1597 he created a thermoscope - an apparatus for raising water using heat. The thermoscope was a small glass ball with a glass tube soldered to it. The difference between a thermoscope and a modern thermometer is that in Galileo's invention, instead of mercury, air expanded. Also, it could only be used to judge the relative degree of heating or cooling of the body, since it did not yet have a scale.

Greenhouse thermometer, 1798. Photo: www.globallookpress.com

Santorio from the University of Padua created his own device with which it was possible to measure the temperature of the human body, but the device was so bulky that it was installed in the courtyard of a house. Santorio's invention had the shape of a ball and an oblong winding tube on which divisions were drawn; the free end of the tube was filled with tinted liquid. His invention dates back to 1626.

In 1657, Florentine scientists improved the Galileo thermoscope, in particular by equipping the device with a bead scale.

Later, scientists tried to improve the device, but all thermometers were air, and their readings depended not only on changes in body temperature, but also on atmospheric pressure.

The first liquid thermometers were described in 1667, but they burst if the water froze, so they began to use wine alcohol to create them. The invention of a thermometer, the data of which would not be determined by changes in atmospheric pressure, occurred thanks to the experiments of the physicist Evangelista Torricelli, a student of Galileo. As a result, the thermometer was filled with mercury, turned upside down, colored alcohol was added to the ball, and the upper end of the tube was sealed.

Single scale and mercury

For a long time, scientists could not find starting points, the distance between which could be divided evenly.

The initial data for the scale were the thawing points of ice and melted butter, the boiling point of water, and some abstract concepts like “a significant degree of cold.”

A thermometer of a modern form, most suitable for household use, with an accurate measurement scale was created by the German physicist Gabriel Fahrenheit. He described his method of creating a thermometer in 1723. Initially, Fahrenheit created two alcohol thermometers, but then the physicist decided to use mercury in the thermometer. The Fahrenheit scale was based on three established points:

the first point was equal to zero degrees - this is the temperature of the composition of water, ice and ammonia;
the second, designated 32 degrees, is the temperature of the mixture of water and ice;
the third, the boiling point of water, was 212 degrees.

The scale was later named after its creator.

Today, the most common is the Celsius scale, the Fahrenheit scale is still used in the USA and England, and the Kelvin scale is used in scientific research.

But it was the Swedish astronomer, geologist and meteorologist Anders Celsius who finally established both constant points - melting ice and boiling water - in 1742. He divided the distance between points into 100 intervals, with the number 100 marking the melting point of ice, and 0 the boiling point of water.

Today, the Celsius scale is used inverted, that is, the melting point of ice is taken as 0°, and the boiling point of water as 100°.

According to one version, the scale was “turned over” by his contemporaries and compatriots, the botanist Carl Linnaeus and the astronomer Morten Stremer, after the death of Celsius, but according to another, Celsius himself turned over his scale on Stremer’s advice.

In 1848, the English physicist William Thomson (Lord Kelvin) proved the possibility of creating an absolute temperature scale, where the reference point is the value of absolute zero: -273.15 ° C - at this temperature further cooling of bodies is no longer possible.

Already in the middle of the 18th century, thermometers became a trade item, and they were made by artisans, but thermometers came into medicine much later, in the middle of the 19th century.

Modern thermometers

If in the 18th century there was a “boom” of discoveries in the field of temperature measurement systems, today work is increasingly being carried out to create methods for measuring temperature.

The scope of application of thermometers is extremely wide and is of particular importance for modern human life. A thermometer outside the window reports the temperature outside, a thermometer in the refrigerator helps control the quality of food storage, a thermometer in the oven allows you to maintain the temperature when baking, and a thermometer measures body temperature and helps assess the causes of poor health.

Mercury thermometers are being replaced by electronic or digital thermometers, which operate on the basis of a built-in metal sensor. There are also special thermal strips and infrared thermometers.

Probably the first device that could, if not measure, then at least estimate temperature was Galileo thermoscope : a flask the size of a chicken egg, the neck of which was thin, like a wheat stalk, was filled halfway with water and immersed in a cup. Despite this simplicity, the device was very sensitive, although it responded, in addition to temperature, to air pressure.

In 1636 the word first appears "thermometer" . That's what it was called device of the Dutchman K. Drebbel — "Drebbel tool" for measuring temperature, having as many as 8 divisions.

Thermos to op Galileo. Drawing from the 17th century.

I. Newto n in work 1701 “On the scale of degrees of heat and cold” described 12 degree scale , 0 0 which corresponded to the freezing temperature of water, and 12° to the body temperature of a healthy person. All these and many other thermometers were gas thermometers: when heated, the air expanded.

The first liquid thermometer, similar to a modern thermometer, was made by the German physicist G. Fahrenheit in 1724. Having been constructing alcohol and mercury thermometers for more than fifteen years, he figured out how to make them identical and more accurate readings: you need to take several points with a known temperature, plot their values on the scales and divide the distances between them.

Fahrenheit took the lowest temperature of the extremely harsh winter of 1709 as 0° and subsequently imitated it in a mixture of table salt and ammonia with ice. As a second reference point, he took the temperature of melting ice and divided this segment by 32 degrees. The third point - the temperature of the human body - turned out to be almost 98, and the boiling point of water was 212.

In A. Gaidar’s film script “The Commandant of the Snow Fortress” there is the following episode:

“The nanny points to Sasha:

- Look, father, he has a fever.

— Every person has a temperature.

“He has a temperature of one hundred degrees,” says Zhenya.

“Not everyone has this,” the doctor agrees.”

The dialogue invariably causes cheerful excitement among young readers, but children in the USA and England, where it is still accepted Fahrenheit , his comedy may not be appreciated: the patient’s temperature is 100° - just a slight fever, which just about anyone can have - 37.8° C.

Used in France and Russia Reaumur scale , created in 1730.

Com A natural thermometer from the early 20th century with Celsius and Reaumur scales.

R. Reaumur. Thermometers of this type were in use in our country until the 30s of the 20th century.

French naturalist, broad-minded scientist, “Pliny of the 18th century,” as his contemporaries called him, R. Reaumur built it in accordance with the thermal expansion of the liquid. Having discovered that when heated, a mixture of water and alcohol expands by 80 thousandths of its volume between the freezing and boiling temperatures of water (the modern value is 0.084), Reaumur divided this interval into 80 degrees.

A little earlier, at the beginning of the 18th century, thermometers of the St. Petersburg academician J. Delisle with a 150-degree scale on the same temperature range were widespread in Russia, but did not last long. Those who drove them out Réaumur thermometers were in use for almost two centuries and only some 50-60 years ago finally gave way to Celsius thermometers with a modern 100-degree scale .

By the end of the 18th century, the number of different temperature scales approached two dozen, which was both inconvenient and unnecessary. In addition, it soon became clear that even carefully calibrated instruments with different liquids show different temperatures. At 50°C, the mercury thermometer showed 43°C with alcohol, the thermometer with olive oil -49°C, with clean water - 25.6°C, and with salt water - 45.4°C.

Found a way out famous English physicist W. Thomson (Lord Kelvin) . In 1848, he proposed to measure not temperature, but the amount of heat that in a certain process called Carnot cycle , is transmitted from a hot body to a cold one: it is determined only by their temperatures and is completely independent of the heated substance. In the thermodynamic, or absolute, temperature scale built on this principle, The unit of temperature is called kelvin .

The thermodynamic scale was good for everyone, me one: in everyday practice, thermal measurements with subsequent calculations are extremely inconvenient, and Carnot cycle, perfectly studied theoretically, is difficult to reproduce outside of a specialized metrological laboratory. Therefore, on its basis in 1968 it was finally established International Practical Temperature Scale (MPTS-68) , which is based on 11 reproducible reference points between triple point in hydrogen (13.81 K) and solidification temperature of gold (1337.58 K ) and diverges from the thermodynamic scale in the boiling region of water by only 0.005 K. This scale is still used today.

Sometimes found in English and American scientific literature absolute scale of the Scotsman W. Rankin (mid-nineteenth century), one of the creators of technical thermodynamics. Its zero point coincides with 0 K, and degree Rankine equal in magnitude to a degree Fahrenheit.

Of all the many temperature scales, only four have reached our time, although this is clearly too much. In science, temperature is expressed in Kelvin, but in life we use Celsius and occasionally see the Reaumur and Fahrenheit scales.

It can be done using special relationships (formulas) or automatically on the pages of our website (follow the link on the left).

Megalov A.

Temperature is one of the most important indicators that is used in various branches of natural science and technology. In physics and chemistry it is used as one of the main characteristics of the equilibrium state of an isolated system, in meteorology - as the main characteristic of climate and weather, in biology and medicine - as the most important quantity that determines vital functions.

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Presentation on the topic: “History of the invention of thermometers” The presentation was made by a student of the Municipal Educational Institution “Gymnasium No. 2” 10 “A” class Megalov Artem

Galileo Galilei's thermoscope In 1592, Galileo Galilei created the thermoscope. The thermoscope was a small glass ball with a soldered glass tube. The ball was heated and the end of the tube was dipped into water. When the ball cooled, the pressure in it decreased, and the water in the tube, under the influence of atmospheric pressure, rose to a certain height. As the weather warmed, the water level in the tubes dropped. The disadvantage of the device was that it could only be used to judge the relative degree of heating or cooling of the body, since it did not yet have a scale.

Florentine thermometers Later, Florentine scientists improved Galileo's thermoscope by adding a scale of beads and pumping out the air from the balloon. In the 17th century, the air thermoscope was converted into an alcohol thermoscope by the Florentine scientist Torricelli. The device was turned upside down, the vessel with water was removed, and alcohol was poured into the tube. The operation of the device was based on the expansion of alcohol when heated - now the readings did not depend on atmospheric pressure. This was one of the first liquid thermometers. Florence thermometer

Two extreme points At that time, the instrument readings were not yet consistent with each other, since no specific system was taken into account when calibrating the scales. In 1694, Carlo Renaldini proposed taking the melting temperature of ice and the boiling point of water as two extreme points.

Fahrenheit's mercury thermometer In 1714, D. G. Fahrenheit made a mercury thermometer. He marked three fixed points on the scale: 32°F is the freezing point of saline solution, 96°F is the human body temperature, and 212°F is the boiling point of water. The Fahrenheit thermometer was used in English-speaking countries until the 70s of the 20th century, and is still used in the USA.

The Frenchman Reaumur scale Another scale was proposed by the French scientist Reaumur in 1730. He experimented with an alcohol thermometer and came to the conclusion that a scale could be constructed in accordance with the thermal expansion of alcohol. Having established that the alcohol he used, mixed with water in a ratio of 5:1, expands in a ratio of 1000:1080, the scientist proposed using a scale from 0 to 80 degrees. Taking the melting temperature of ice as 0°, and the boiling temperature of water at normal atmospheric pressure as 80°.

Anders Celsius scale In 1742, Anders Celsius proposed a scale for a mercury thermometer in which the interval between extreme points was divided into 100 degrees. At the same time, at first the boiling point of water was designated as 0 °, and the melting temperature of ice as 100 °. However, in this form the scale turned out to be inconvenient, and later astronomer M. Stremer and botanist K. Linnaeus decided to swap the extreme points.

Various thermometers and scales M. V. Lomonosov proposed a liquid thermometer with a scale of 150. I. G. Lambert was responsible for the creation of an air thermometer with a scale of 375 °, where one thousandth of the expansion of air volume was taken as one degree. There were also attempts to create a thermometer based on the expansion of solids. So in 1747, the Dutchman P. Muschenbrug used the expansion of an iron bar to measure the melting point of a number of metals.

Absolute Kelvin scale In the temperature scales discussed above, the reference point was arbitrary. At the beginning of the 19th century, the English scientist Lord Kelvin proposed an absolute thermodynamic scale. At the same time, Kelvin substantiated the concept of absolute zero, denoting the temperature at which the thermal movement of molecules ceases. In Celsius it is -273.15 °C.

How it was then This is the basic history of the emergence of the thermometer and thermometric scales. Today, thermometers with the Celsius, Fahrenheit (in the USA), and Kelvin scales are used in scientific research

As it is now Currently, temperature is measured using instruments whose action is based on the various thermometric properties of liquids, gases and solids. Today, there are many devices used in industry, in everyday life, and in scientific research - expansion thermometers and laboratory equipment, thermoelectric and resistance thermometers, as well as pyrometric thermometers that allow you to measure temperature in a non-contact way.