Temperature scales

The temperature scale is a specific functional numerical relationship of temperature with the values ​​of the measured thermometric property. In this regard, it seems possible to construct a temperature scale based on the choice of any thermometric property. At the same time, there is not a single thermometric property that varies linearly with

temperature change and does not depend on other factors in a wide range of temperature measurements. The first scales appeared in the 18th century. To build them, two references were chosen, or fixed points t1 and t2, which are the phase equilibrium temperatures of pure substances. temperature difference t 1 -t 2 called the main temperature range.

Fahrenheit (1715), Réaumur (1776) and Celsius (1742) based their scales on the assumption of a linear relationship between temperature t and thermometric property, which was used as the expansion of the liquid volume V(formula 14.27) /8/

t=a+bV,(14.27)

where a and b- constant coefficients.

Substituting into equation (14.27) V=V1 at t=t1 and V=V2 at t=t2, after transformations we obtain the equation (14.28) of the temperature scale /8/

In Fahrenheit, Réaumur and Celsius scales, the melting point of ice t1 corresponded to +32, 0 and 0 °, and the boiling point of water t2- 212, 80 and 100°. Basic spacing t2–t1 in these scales, respectively, is divided into N= 180, 80 and 100 equal parts, and 1/N part of each of the intervals is called degrees Fahrenheit - t° F, degrees Réaumur - t° R and degrees Celsius t °С. Thus, for scales built according to this principle, the degree is not a unit of measurement, but is a single interval - the scale scale.

To convert the temperature from one specified scale to another, use the relation (14.29)

t°С= 1.25° R=-(5/9)( - 32), (14.29)

Later it was found that the readings of thermometers that have different thermometric substances (for example, mercury, alcohol, etc.), using the same thermometric property and a uniform degree scale, coincide only at reference points, and at other points the readings diverge. The latter is especially noticeable when measuring temperatures, the values ​​of which are located far from the main interval.

This circumstance is explained by the fact that the relationship between temperature and thermometric properties is actually nonlinear and this nonlinearity is different for different thermometric substances. In particular, in the case under consideration, the nonlinearity between the temperature and the change in the liquid volume is explained by the fact that the temperature coefficient of the volumetric expansion of the liquid itself changes with temperature, and this change is different for different dropping liquids.

On the basis of the described principle of construction, any number of temperature scales can be obtained, which differ significantly from each other. Such scales are called conditional, and the scales of these scales are called conditional degrees. The problem of creating a temperature scale independent of the thermometric properties of substances was solved in 1848 by Kelvin, and the scale he proposed was called thermodynamic. Unlike conditional temperature scales, the thermodynamic temperature scale is absolute.

Thermodynamic temperature scale based on the second law of thermodynamics. In accordance with this law, the efficiency of a heat engine operating on a reversible Carnot cycle is determined only by the heater temperatures T N and refrigerator T X and does not depend on the properties of the working substance, thus the efficiency is calculated by the formula (14.30) /8/

(14.30)

where Q N and QX- respectively, the amount of heat received by the working substance from the heater and given to the refrigerator.

Kelvin proposed to use the equation (14.31) /8/ to determine the temperature

T N / T X \u003d Q N / Q X , (14.31)

Therefore, by using one object as a heater and another as a refrigerator, and performing a Carnot cycle between them, one can determine the ratio of the temperatures of the objects by measuring the ratio of heat taken from one object and given to another. The resulting temperature scale does not depend on the properties of the working (thermometric) substance and is called the absolute temperature scale. In order for the absolute temperature (and not just the ratio) to have a certain value, it was proposed to take the difference in thermodynamic temperatures between the boiling points of water T KV and melting ice T TL, equal to 100 °. The adoption of such a value of the difference pursued the goal of preserving the continuity of the numerical expression of the thermodynamic temperature scale from the centigrade Celsius temperature scale. Thus, denoting the amount of heat received from the heater (boiling water) and given to the refrigerator (melting ice), respectively, through Q HF and Q TL and accepting T KV - T TL == 100, using (14.31), we obtain the equality (14.32) and (14.33)

(14.32)

(14.33)

For any temperature T heater at a constant temperature T TL refrigerator and the amount of heat Q TL, given to it by the working substance of the Carnot machine, we will have the equality (14.34) /8/

(14.34)

Expression (14.34) is the equation centigrade thermodynamic temperature scale and shows that the temperature value T on this scale is linearly related to the amount of heat Q obtained by the working substance of the heat engine when it completes the Carnot cycle, and, as a result, does not depend on the properties of the thermometric substance. One degree of thermodynamic temperature is taken to be such a difference between the temperature of the body and the melting temperature of ice, at which the work done in the reversible Carnot cycle is equal to 1/100 of the work done in the Carnot cycle between the boiling point of water and the melting of ice (provided that in both cycles the amount of heat given off to the refrigerator is the same). From expression (14.30) it follows that at the maximum value should be equal to zero T X. This lowest temperature was called absolute zero by Kelvin. The temperature on the thermodynamic scale is denoted T K. If in an expression describing the Gay-Lussac gas law: (where Ro- pressure at t=0 °C; - temperature coefficient of pressure), substitute the temperature value equal to - , then the gas pressure P t will become zero. It is natural to assume that the temperature at which the limiting minimum gas pressure is provided is itself the lowest possible, and is taken as zero on the absolute Kelvin scale. Therefore, the absolute temperature

From the Boyle-Mariotte law, it is known that for gases the temperature coefficient of pressure a is equal to the temperature coefficient of volume expansion. It was experimentally found that for all gases at pressures tending to zero, in the temperature range 0-100 ° C, the temperature coefficient of volume expansion = 1/273.15.

So the null value absolute temperature corresponds to °C. The melting temperature of ice on an absolute scale will be To\u003d\u003d 273.15 K. Any temperature in the absolute Kelvin scale can be defined as (where t temperature in °C). It should be noted that one degree Kelvin (1 K) corresponds to one degree Celsius (1 °C), since both scales are based on the same fixed points. The thermodynamic temperature scale based on two reference points (the melting temperature of ice and the boiling point of water) had insufficient measurement accuracy. In practice, it is difficult to reproduce the temperatures of these points, since they depend on pressure changes, as well as minor impurities in the water. Kelvin and, independently of him, D. I. Mendeleev expressed their views on the expediency of constructing a thermodynamic temperature scale from one reference point. In 1954, the Advisory Committee on Thermometry of the International Committee for Weights and Measures adopted a recommendation to move to the definition of a thermodynamic scale using one reference point - the triple point of water (the equilibrium point of water in the solid, liquid and gaseous phases), which is easily reproduced in special vessels with with an error of no more than 0.0001 K. The temperature of this point is taken equal to 273.16 K, i.e. above the temperature of the ice melting point by 0.01 K. This number was chosen so that the temperature values ​​on the new scale would practically not differ from the old Celsius scale with two fixed points. The second reference point is absolute zero, which is not experimentally realized, but has a strictly fixed position. In 1967, the XIII General Conference on Weights and Measures clarified the definition of the unit of thermodynamic temperature in the following edition: "Kelvin-1/273.16 part of the thermodynamic temperature of the triple point of water." Thermodynamic temperature can also be expressed in degrees Celsius: t= T- 273.15 K. The use of the second law of thermodynamics, proposed by Kelvin in order to establish the concept of temperature and construct an absolute thermodynamic temperature scale that does not depend on the properties of a thermometric substance, is of great theoretical and fundamental importance. However, the implementation of this scale using a heat engine operating according to a reversible Carnot cycle as a thermometer is practically impossible.

The thermodynamic temperature is equivalent to the gas thermal temperature used in the equations describing the laws of ideal gases. gas thermal temperature scale They are built on the basis of a gas thermometer, in which a gas is used as a thermometric substance, approaching the properties of an ideal gas. Thus, the gas thermometer is a real tool for reproducing the thermodynamic temperature scale. There are three types of gas thermometers: constant volume, constant pressure, and constant temperature. Usually a gas thermometer of constant volume is used (Figure 14.127), in which the change in gas temperature is proportional to the change in pressure. The gas thermometer consists of a cylinder 1 and connecting tube 2, filled through the valve 3 hydrogen, helium or nitrogen (for high temperatures). Connecting tube 2 connected to a tube 4 two-pipe pressure gauge, in which the tube 5 can be moved up or down thanks to the flexible connecting hose 6. When the temperature changes, the volume of the system filled with gas changes, and to bring it to its original value, the tube 5 move vertically until the level of mercury in the tube 4 not aligned with axis X-X. At the same time, the column of mercury in the tube 5, measured from the level X-X, will correspond to the gas pressure R in a balloon.

Figure 14.127 - Diagram of a gas thermometer

commonly measured temperature T determined relative to some reference point, for example, relative to the temperature of the triple point of water T0, at which the pressure of the gas in the cylinder will be Ro. The desired temperature is calculated by the formula (14.35)

(14.35)

Gas thermometers are used in the interval ~ 2- 1300 K. The error of gas thermometers is within 3-10-3 - 2-10-2 K depending on the measured temperature. Achieving such high precision measurements -difficult task, which requires taking into account numerous factors: deviations of the properties of a real gas from an ideal one, the presence of impurities in the gas, sorption and desorption of gas by the walls of the cylinder, diffusion of gas through the walls, change in the volume of the cylinder from temperature, temperature distribution along the connecting tube.

Due to the great complexity of working with gas thermometers, attempts were made to find more simple methods reproduction of the thermodynamic temperature scale.

On the basis of studies carried out in various countries at the VII General Conference on Weights and Measures in 1927, it was decided to replace the thermodynamic scale "practical" temperature scale and call her international temperature scale. This scale was consistent with the centigrade thermodynamic scale as closely as the level of knowledge of that time allowed.

To build the international temperature scale, six reproducible reference points were chosen, the temperatures of which on the thermodynamic scale were carefully measured in various countries using gas thermometers and the most reliable results were accepted. With the help of fiducial points, reference instruments are calibrated to reproduce the international temperature scale. In the intervals between the reference points, the temperature values ​​are calculated according to the proposed interpolation formulas that establish the relationship between the readings of reference instruments and the temperature according to international scale. In 1948, 1960 and 1968 a number of clarifications and additions were made to the provisions on the international temperature scale, since, on the basis of improved measurement methods, differences were found between this scale and the thermodynamic scale, especially at high temperatures, and also due to the need to extend the temperature scale to lower temperatures. At present, the improved scale adopted at the XIII Conference on Weights and Measures under the name "International Practical Temperature Scale 1968" (IPTP-68) is in force. The definition "practical" indicates that this temperature scale generally does not coincide with the thermodynamic one. MPTSh-68 temperatures are supplied with an index ( T68 or t68).

MPTSh-68 is based on 11 main reference points listed in Table 9. Along with the main ones, there are 27 secondary fixed points covering the temperature range from 13.956 to 3660 K (from -259.194 to 3387 °C). The numerical values ​​of temperatures given in Table 14.4 correspond to the thermodynamic scale and are determined using gas thermometers.

As a reference thermometer in the temperature range from 13.81 to 903.89 K (630.74 ° C - the solidification point of antimony - the secondary reference point), a platinum resistance thermal converter is taken. This interval is divided into five subintervals, for each of which interpolation formulas are defined in the form of polynomials up to the fourth degree. In the temperature range from 903.89 to 1337.58 K, a reference platinum-platinum-rhodium thermoelectric thermometer is used. The interpolation formula that relates the thermoelectromotive force to the temperature here is a polynomial of the second degree.

For temperatures above 1337.58 K (1064.43°C), MPTS-68 is reproduced using a quasi-monochromatic thermometer using Planck's radiation law.

Table 14.4 - Main fiducial points of IPTS-68

There are several different temperature units.

The most famous are the following:

Degree Celsius - used in the International System of Units (SI) along with the kelvin.

The degree Celsius is named after the Swedish scientist Anders Celsius, who in 1742 proposed a new scale for measuring temperature.

The original definition of the degree Celsius depended on the definition of standard atmospheric pressure, because both the boiling point of water and the melting point of ice depend on pressure. This is not very convenient for standardizing the unit of measurement. Therefore, after the adoption of the kelvin K as the basic unit of temperature, the definition of the degree Celsius was revised.

According to the modern definition, a degree Celsius is equal to one kelvin K, and the zero of the Celsius scale is set so that the temperature of the triple point of water is 0.01 °C. As a result, the Celsius and Kelvin scales are shifted by 273.15:

In 1665, the Dutch physicist Christian Huygens, together with the English physicist Robert Hooke, first proposed using the melting points of ice and boiling points of water as reference points for the temperature scale.

In 1742, the Swedish astronomer, geologist and meteorologist Anders Celsius (1701-1744) developed a new temperature scale based on this idea. Initially, 0° (zero) was the boiling point of water, and 100° was the freezing point of water (the melting point of ice). Later, after the death of Celsius, his contemporaries and compatriots, the botanist Carl Linnaeus and the astronomer Morten Strömer, used this scale upside down (for 0 ° they began to take the temperature of melting ice, and for 100 ° - boiling water). In this form, the scale is used to this day.

According to one account, Celsius himself turned his scale on the advice of Strömer. According to other sources, the scale was turned over by Carl Linnaeus in 1745. And according to the third, the scale was turned over by Celsius's successor Morten Strömer, and in the 18th century such a thermometer was widely used under the name "Swedish thermometer", and in Sweden itself under the name Strömer, but the famous Swedish chemist Jöns Jakob Berzelius in his work "A Guide to Chemistry ” called the scale “Celsius” and since then the centigrade scale has been named after Anders Celsius.

Degree Fahrenheit.

It is named after the German scientist Gabriel Fahrenheit, who in 1724 proposed a scale for measuring temperature.

On the Fahrenheit scale, the melting point of ice is +32°F and the boiling point of water is +212°F (at normal atmospheric pressure). In this case, one degree Fahrenheit is equal to 1/180 of the difference between these temperatures. The range 0…+100 °F Fahrenheit roughly corresponds to the range -18…+38 °C Celsius. Zero on this scale is defined as the freezing point of a mixture of water, salt and ammonia (1:1:1), and 96 °F is taken as the normal temperature of the human body.

Kelvin (before 1968 degrees Kelvin) is a unit of thermodynamic temperature in the International System of Units (SI), one of the seven basic SI units. Proposed in 1848. 1 kelvin is equal to 1/273.16 of the thermodynamic temperature of the triple point of water. The beginning of the scale (0 K) coincides with absolute zero.

Conversion to degrees Celsius: ° С \u003d K−273.15 (the temperature of the triple point of water is 0.01 ° C).

The unit is named after the English physicist William Thomson, who was awarded the title of Lord Kelvin Larg of Ayrshire. In turn, this title comes from the River Kelvin, which flows through the territory of the university in Glasgow.

	Kelvin	Degree Celsius	Fahrenheit
Absolute zero
Boiling point of liquid nitrogen
Sublimation (transition from solid state into gaseous) dry ice
Intersection point of Celsius and Fahrenheit scales
Ice melting point
Triple point of water
Normal human body temperature
Boiling point of water at a pressure of 1 atmosphere (101.325 kPa)

Degree Reaumur - a unit of temperature in which the freezing and boiling points of water are taken as 0 and 80 degrees, respectively. Proposed in 1730 by R. A. Réaumur. The Réaumur scale has practically fallen into disuse.

Römer degree is a currently unused unit of temperature.

The Römer temperature scale was created in 1701 by the Danish astronomer Ole Christensen Römer. She became the prototype of the Fahrenheit scale, which Roemer visited in 1708.

Zero degrees is the freezing point of salt water. The second reference point is the temperature of the human body (30 degrees according to Roemer's measurements, i.e. 42 °C). Then the freezing temperature fresh water is obtained as 7.5 degrees (1/8 of the scale), and the boiling point of water is 60 degrees. Thus, the Römer scale is 60 degrees. This choice seems to be explained by the fact that Römer is primarily an astronomer, and the number 60 has been the cornerstone of astronomy since Babylonian times.

Degree Rankine - a unit of temperature in the absolute temperature scale, named after the Scottish physicist William Rankin (1820-1872). Used in English-speaking countries for engineering thermodynamic calculations.

The Rankine scale starts at absolute zero, the freezing point of water is 491.67°Ra, and the boiling point of water is 671.67°Ra. The number of degrees between the freezing and boiling points of water on the Fahrenheit and Rankine scales is the same and is equal to 180.

The relationship between Kelvin and degrees Rankine: 1 K = 1.8 °Ra, degrees Fahrenheit are converted to degrees Rankine using the formula °Ra = °F + 459.67.

Degree of Delisle is a now obsolete unit of temperature measurement. It was invented by the French astronomer Joseph Nicolas Delisle (1688-1768). The Delisle scale is similar to the Réaumur temperature scale. It was used in Russia until the 18th century.

Peter the Great invited the French astronomer Joseph Nicolas Delisle to Russia, establishing the Academy of Sciences. In 1732, Delisle created a thermometer using mercury as the working fluid. The boiling point of water was chosen as zero. For one degree, such a change in temperature was taken, which led to a decrease in the volume of mercury by one hundred-thousandth.

Thus, the melting temperature of ice was 2400 degrees. However, later such a fractional scale seemed redundant, and already in the winter of 1738, Delisle's colleague at the St. Petersburg Academy, physician Josias Weitbrecht (1702-1747), reduced the number of steps from the boiling point to the freezing point of water to 150.

The “inversion” of this scale (as well as the original version of the Celsius scale) compared to those currently accepted is usually explained by purely technical difficulties associated with the calibration of thermometers.

Delisle's scale was widely used in Russia, and his thermometers were used for about 100 years. This scale was used by many Russian academics, including Mikhail Lomonosov, who, however, "turned" it, placing zero at the freezing point, and 150 degrees at the boiling point of water.

Degree Hooke - historical unit of temperature. The Hooke scale is considered the very first temperature scale with a fixed zero.

The prototype for the scale created by Hooke was a thermometer that came to him in 1661 from Florence. In Hooke's Micrographia, published a year later, there is a description of the scale he developed. Hooke defined one degree as a change in the volume of alcohol by 1/500, that is, one degree of Hooke is equal to approximately 2.4 ° C.

In 1663 the members of the Royal Society agreed to use Hooke's thermometer as the standard and to compare the readings of other thermometers with it. The Dutch physicist Christian Huygens in 1665, together with Hooke, proposed using the temperatures of melting ice and boiling water to create a temperature scale. It was the first scale with a fixed zero and negative values.

Degree Dalton is the historical unit of temperature. It has no definite meaning (in terms of traditional temperature scales such as Kelvin, Celsius or Fahrenheit) because the Dalton scale is logarithmic.

The Dalton scale was developed by John Dalton to take measurements at high temperatures, since conventional uniform-scale thermometers gave errors due to uneven expansion of the thermometric fluid.

Zero on the Dalton scale corresponds to zero Celsius. A distinctive feature of the Dalton scale is that absolute zero in it is equal to − ∞°Da, i.e. it is an unattainable value (which is actually the case, according to the Nernst theorem).

Degree Newton is a unit of temperature that is no longer in use.

Newton's temperature scale was developed by Isaac Newton in 1701 for thermophysical research and probably became the prototype of the Celsius scale.

As a thermometric fluid, Newton used linseed oil. Newton took the freezing point of fresh water as zero degrees, and he designated the temperature of the human body as 12 degrees. Thus, the boiling point of water became equal to 33 degrees.

Leiden degree - historical unit of temperature used at the beginning of the 20th century to measure cryogenic temperatures below −183 °C.

This scale originates from Leiden, where Kamerlingh Onnes' laboratory was located since 1897. In 1957, H. van Dijk and M. Dureau introduced the L55 scale.

The boiling point of standard liquid hydrogen (−253 °C), consisting of 75% orthohydrogen and 25% parahydrogen, was taken as zero degrees. The second reference point is the boiling point of liquid oxygen (−193 °C).

Planck temperature , named after the German physicist Max Planck, the unit of temperature, denoted T P , in the Planck system of units. This is one of the Planck units, which represents the fundamental limit in quantum mechanics. The modern physical theory is not capable of describing anything hotter due to the lack of a developed theory in it. quantum theory gravity. Above the Planck temperature, the energy of the particles becomes so large that the gravitational forces between them become comparable to the rest of the fundamental interactions. This is the temperature of the Universe at the first moment (Planck time) of the Big Bang, according to the current ideas of cosmology.

On February 22, 1857, the German physicist Heinrich Rudolf Hertz was born, after whom the unit of frequency was named. You have seen his name more than once in school textbooks on physics. the site recalls famous scientists whose discoveries immortalized their names in science.

Blaise Pascal (1623−1662)

“Happiness lies only in peace, not in fuss,” said the French scientist Blaise Pascal. It seems that he himself did not strive for happiness, putting his whole life on persistent research in mathematics, physics, philosophy and literature. The future scientist was educated by his father, having compiled an extremely complex program in the field of natural sciences. Already at the age of 16, Pascal wrote the work "Experiment on Conic Sections". Now the theorem about which this work was told is called Pascal's theorem. The brilliant scientist became one of the founders mathematical analysis and probability theory, and also formulated the main law of hydrostatics. Free time Pascal devoted to literature. His pen belongs to the "Letters of the Provincial", ridiculing the Jesuits, and serious religious works.

Pascal devoted his free time to literature

A unit of pressure measurement, a programming language and a French university were named after the scientist. “Random discoveries are made only by trained minds,” said Blaise Pascal, and in this he was certainly right.

Isaac Newton (1643−1727)

Doctors believed that Isaac was unlikely to live to old age and suffer from serious diseases.As a child, his health was very poor. Instead, the English scientist lived for 84 years and laid the foundations modern physics. Newton devoted all his time to science. His most famous discovery was the law of gravity. The scientist formulated three laws classical mechanics, the fundamental theorem of analysis, made important discoveries in color theory and invented the mirror telescope.The unit of force, the international award in the field of physics, 7 laws and 8 theorems are named after Newton.

Daniel Gabriel Fahrenheit 1686−1736

The unit of temperature measurement, degrees Fahrenheit, is named after the scientist.Daniel came from a wealthy merchant family. His parents hoped that he would continue the family business, so the future scientist studied trade.

The Fahrenheit scale is still widely used in the US.

If at some point he had not shown interest in applied natural sciences, then there would not be a system for measuring temperature, which for a long time dominated Europe. However, it cannot be called ideal, since for 100 degrees the scientist took the body temperature of his wife, who, unfortunately, had a cold at that time.Despite the fact that in the second half of the 20th century the system of the German scientist was replaced by the Celsius scale, the Fahrenheit temperature scale is still widely used in the United States.

Anders Celsius (1701−1744)

It is a mistake to think that the life of a scientist proceeded in the study

The degree Celsius was named after the Swedish scientist.It is not surprising that Anders Celsius devoted his life to science. His father and both grandfathers taught at a Swedish university, and his uncle was an orientalist and botanist. Anders was primarily interested in physics, geology and meteorology. It is a mistake to think that the life of a scientist was spent only in his office. He participated in expeditions to the equator, to Lapland and studied the Northern Lights. In the meantime, Celsius invented the temperature scale, in which 0 degrees was taken as the boiling point of water, and 100 degrees as the melting temperature of ice. Subsequently, the biologist Carl Linnaeus converted the Celsius scale, and today it is used throughout the world.

Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta (1745−1827)

People around noticed in Alessandro Volta the makings of a future scientist as early as childhood. At the age of 12, an inquisitive boy decided to explore a spring near the house, where pieces of mica shone, and almost drowned.

Alessandro received his primary education at the Royal Seminary in the Italian city of Como. At 24, he defended his dissertation.

Alessandro Volta received the title of senator and count from Napoleon

Volta designed the world's first chemical source electric current- "Voltaic pillar". He successfully demonstrated a revolutionary discovery for science in France, for which he received the title of senator and count from Napoleon Bonaparte. Unit of measure named after scientist electrical voltage— Volt.

Andre-Marie Ampère (1775−1836)

The contribution of the French scientist to science is difficult to overestimate. It was he who introduced the terms "electric current" and "cybernetics". The study of electromagnetism allowed Ampère to formulate the law of interaction between electric currents and prove the theorem on the circulation of a magnetic field.The unit of electric current is named after him.

Georg Simon Ohm (1787−1854)

He received his primary education at a school where only one teacher worked. The future scientist studied the works on physics and mathematics on his own.

George dreamed of unraveling the phenomena of nature, and he quite succeeded. He proved the relationship between resistance, voltage and current in a circuit. Ohm's law knows (or would like to believe that he knows) every student.Georg also received a PhD and shared his knowledge with German university students over the years.The unit of electrical resistance is named after him.

Heinrich Rudolf Hertz (1857−1894)

Without the discoveries of the German physicist, television and radio would simply not exist. Heinrich Hertz investigated the electric and magnetic fields, experimentally confirmed Maxwell's electromagnetic theory of light. For his discovery, he received several prestigious scientific awards, including even the Japanese Order of the Sacred Treasure.

We chose this topic because we constantly encounter the concepts of "temperature", "temperature measurement", "thermometer" both when considering physical or chemical processes in science and production, and in everyday life, when we put a thermometer on a patient or look at an alcohol thermometer outside the window to find out whether to wear a warm coat. However, usually in this case, by temperature, we simply understand the degree of heating of the body and do not think about what temperature is from a physical point of view. Temperature is one of the most frequently measured physical quantities, since there is practically no area of ​​​​activity where it was not necessary to measure and regulate temperature, it is also one of the most important environmental factors on which survival on the planet depends, its forms and types. Human life also directly depends on the ambient temperature.

In the International System of Units (SI), thermodynamic temperature is used as one of the seven basic physical quantities included in the International System of Units, and its unit is the kelvin, which is, respectively, one of the seven basic SI units.

Purpose of the work: To get acquainted with the concept of temperature.

Tasks: View temperature scales, get an idea about some types of thermometers, their principles of operation, work out tasks, conduct an experiment.

1.Temperature,T.

Temperature(from Latin. temperature— proper mixing, normal state) — a scalar* physical quantity characterizing the state of thermodynamic equilibrium** of a macroscopic system***. The temperature of all parts of a system in equilibrium is the same. If the system is not in equilibrium, then heat transfer occurs between its parts that have different temperatures (energy transfer from more heated parts of the system to less heated parts), leading to equalization of temperatures in the system.

Temperature refers to intensive quantities that do not depend on the mass of the system.

Intuitive concept temperature appeared as a measure of the gradation of our sensations of heat and cold; at the household level, temperature is perceived as a parameter that serves to quantitatively describe the degree of heating of a material object.

The word "temperature" arose at a time when people believed that hotter bodies contained large quantity special substance - caloric, than in less heated ones. Therefore, temperature was perceived as the strength of a mixture of body substance and caloric. For this reason, the units of measure for the strength of alcoholic beverages and temperature are called the same - degrees.

From the fact that temperature is the kinetic energy of molecules, it is clear that it is most natural to measure it in energy units (i.e. in the SI system in joules). However, temperature measurement began long before the creation of molecular kinetic theory, so practical scales measure temperature in conventional units - degrees.

The average kinetic energy of the chaotic translational motion of body molecules is proportional to the thermodynamic (absolute) temperature:

(k=1.38*10^-23J/k-Boltzmann's constant(is a coefficient that converts temperature from degree measure(K) to energy measure(J), the factor 3/2 was introduced for convenience, due to which factors disappear in other formulas.)

The average speed of thermal motion.

As follows from the formula

a cold gas differs from a gas heated to a high temperature by the energy of the chaotic motion of molecules, therefore the chaotic motion of molecules is called thermal.

Average (more precisely, root-mean-square) speed of thermal motion of molecules can be expressed in terms of the gas temperature using the formula

The last formula can be reduced to a more convenient form if we express the mass of the molecule and denote ( R ~ 8, 31 J / (K. mol) is called the universal gas constant)

* A scalar quantity is a quantity each value of which can be expressed by a single real number. That is, a scalar quantity is determined only by its value, in contrast to a vector, which, in addition to its value, has a direction. Scalar quantities include length, area, time, temperature, etc.

**Thermodynamic equilibrium is the state of a system in which the macroscopic quantities of this system (temperature, pressure, volume) remain unchanged in time under conditions of isolation from the environment.

*** Macroscopic system - a system consisting of a large number particles and does not require the involvement of microscopic characteristics of individual particles for its description.

****Isolated system ( closed system) is a thermodynamic system that does not exchange with environment neither matter nor energy.

2. Temperature scales.

Temperature scales, methods of dividing into parts of temperature intervals measured by thermometers by changing any convenient for measurements physical property object, other things being equal, uniquely dependent on temperature (volume, pressure, electrical resistance, radiation intensity, refractive index, speed of sound, etc.) and called thermometric property. To build a temperature scale, assign it numerical values two fixed points ( fixed points temperature), such as the melting point of ice and the boiling point of water. Dividing the temperature difference of reference points ( main temperature range) for an arbitrarily chosen number of parts, a temperature unit is obtained, and by setting, again arbitrarily, a functional relationship between the selected thermometric property and temperature, it becomes possible to calculate the temperature according to a given temperature scale.

It is clear that constructed in this way empirical temperature scale is optional and conditional. Therefore, it is possible to create any number of temperature scales that differ in the chosen thermometric properties, the accepted functional dependences of temperature on them (in the simplest case, the relationship between a thermometric property and temperature is assumed to be linear) and the temperatures of reference points.

Examples of temperature scales are Celsius, Réaumur, Fahrenheit, Rankine and Kelvin.

The conversion of temperature from one temperature scale to another, which differs in thermometric properties, is impossible without additional experimental data.

The fundamental drawback of empirical temperature scales - their dependence on the chosen thermometric property - is absent from the absolute (thermodynamic) temperature scale.

2.1. Kelvin scale.

The kelvin (symbol: K) is a unit of thermodynamic temperature in the International System of Units (SI), one of the seven basic SI units. Proposed in 1848. One kelvin is equal to 1/273.16 of the thermodynamic temperature of the triple point of water*. The beginning of the scale (0 K) coincides with absolute zero**.

Conversion to degrees Celsius: ° С \u003d K−273.15 (the temperature of the triple point of water is 0.01 ° C).

The unit is named after the English physicist William Thomson, who was awarded the title of Lord Kelvin Larg of Ayrshire. In turn, this title comes from the River Kelvin, which flows through the territory of the university in Glasgow.

Until 1968, the kelvin was officially called the Kelvin degree.

* The triple point of water is strictly defined values ​​of temperature and pressure at which water can exist simultaneously and in equilibrium in the form of three phases - in solid, liquid and gaseous states. The triple point of water is a temperature of 273.16 K and a pressure of 611.657 Pa.

** Absolute zero temperature (less often - absolute zero temperature) - the minimum temperature limit that a physical body can have in the universe. Absolute zero serves as the reference point for an absolute temperature scale, such as the Kelvin scale. In 1954, the X General Conference on Weights and Measures established the thermodynamic temperature scale from one reference point - the triple point of water, the temperature of which is taken to be 273.16 K (exactly), which corresponds to 0.01 ° C, so that on the Celsius scale absolute zero corresponds to temperature -273.15°C.

2.2. Reaumur scale.

Degree Réaumur (°R)- a unit of temperature in which the freezing and boiling points of water are taken as 0 and 80 degrees, respectively. Proposed in 1730 by R. A. Réaumur. The Réaumur scale has practically fallen into disuse.

According to Réaumur's expectations, alcohol expands by approximately 8% (by 8.4% according to the calculation: the expansion coefficient of alcohol is 0.00108 K-) when heated from the melting temperature of ice to the boiling point (≈78 degrees Celsius). Therefore, Réaumur set this temperature as 80 degrees on his scale, on which one degree corresponded to the expansion of alcohol by 1 thousandth, and the zero of the scale was chosen as the freezing point of water. However, due to the fact that not only alcohol was used as a liquid in those days, but also its various aqueous solutions, then many manufacturers and users of thermometers mistakenly believed that 80 degrees Réaumur is the boiling point of water. And after the widespread introduction of mercury as a liquid for thermometers, as well as the emergence and spread of the Celsius scale, by the end of the 18th century, the Réaumur scale was finally redefined in this way. From the equation 100 degrees Celsius = 80 degrees Réaumur, we get 1 °C = 0.8 °R (correspondingly 1 °R = 1.25 °C). Although in fact the original Réaumur scale should be 1 °R = 0.925 °C. Even during the life of Réaumur, the boiling point of water was measured in degrees of his scale (but not with an alcohol thermometer - this was impossible). Jean Tillet, in the presence of Jean-Antoine Nollet, obtained a value of 85. But all subsequent measurements gave values ​​​​from 100 to 110 degrees. If we use the above modern data, then the boiling point of water in degrees Réaumur is 108. (In 1772, in France, the boiling point of water, equal to 110 degrees Réaumur, was adopted as the standard).

2.3. Celsius.

Degree Celsius(symbol: °C) is a common unit of temperature used in the International System of Units (SI) along with the kelvin.

The degree Celsius is named after the Swedish scientist Anders Celsius, who in 1742 proposed a new scale for measuring temperature.

The original definition of the degree Celsius depended on the definition of standard atmospheric pressure, because both the boiling point of water and the melting point of ice depend on pressure. This is not very convenient for standardizing the unit of measurement. Therefore, after the adoption of the kelvin K as the basic unit of temperature, the definition of the degree Celsius was revised.

According to the modern definition, a degree Celsius is equal to one kelvin K, and the zero of the Celsius scale is set so that the temperature of the triple point of water is 0.01 °C. As a result, the Celsius and Kelvin scales are shifted by 273.15:

Story:

In 1665, the Dutch physicist Christian Huygens, together with the English physicist Robert Hooke, first proposed using the melting points of ice and boiling points of water as reference points for the temperature scale.

In 1742, the Swedish astronomer, geologist and meteorologist Anders Celsius (1701–1744) developed a new temperature scale based on this idea. Initially, 0° (zero) was the boiling point of water, and 100° was the freezing point of water (the melting point of ice). Later, after the death of Celsius, his contemporaries and compatriots, the botanist Carl Linnaeus and the astronomer Morten Strömer, used this scale upside down (for 0 ° they began to take the temperature of melting ice, and for 100 ° - boiling water). In this form, the scale is used to this day.

2.4. Fahrenheit.

Fahrenheit degree(symbol: °F) is a temperature unit. It is named after the German scientist Gabriel Fahrenheit, who in 1724 proposed a scale for measuring temperature.

On the Fahrenheit scale, the melting point of ice is +32 °F, and the boiling point of water is +212 °F(at normal atmospheric pressure). In this case, one degree Fahrenheit is equal to 1/180 of the difference between these temperatures. Range 0…+100 °F on the Fahrenheit scale approximately corresponds to the range -18 ... +38 °C on the Celsius scale. Zero on this scale is determined by the freezing point of a mixture of water, salt and ammonia (1:1:1), and for 96 °F the normal temperature of the human body.

Converting from Fahrenheit to Celsius:

Fahrenheit was widely used in all English-speaking countries until the 1960s, when most of them switched to the metric system with degrees Celsius, however, Fahrenheit is still sometimes used in these countries.

Currently, the Fahrenheit degree is used in everyday life as the main unit of temperature in the following countries: USA and dependent territories(Guam, Virgin Islands, Palau, Puerto Rico, etc.), Belize, Bermuda, Jamaica.

2.5. Rankin scale.

Rankin scale(measured in degrees Rankin - °Ra) - an absolute temperature scale, named after the Scottish physicist William Rankin (1820-1872). Used in English-speaking countries for engineering thermodynamic calculations.

The Rankine scale starts at absolute zero, the freezing point of water is 491.67°Ra, and the boiling point of water is 671.67°Ra. The number of degrees between the freezing and boiling points of water on the Fahrenheit and Rankine scales is the same and is equal to 180.

The relationship between Kelvin and degrees Rankine: 1 K = 1.8 °Ra, degrees Fahrenheit are converted to degrees Rankine using the formula °Ra = °F + 459.67. The number of degrees between the freezing and boiling points of water on the Fahrenheit and Rankine scales is the same and equals 180. This is different from the absolute Kelvin scale, where 1 kelvin corresponds to 1 ° C.

Temperature Conversion Chart:

3. Thermometers.

Thermometer(from the Greek terme - heat, metreo - I measure) - a device for measuring temperature: air, water, soil, human body and others physical bodies. Thermometers are used in meteorology, hydrology, medicine and other sciences and industries.

Invention history:

It is believed that the famous Italian scientist Galileo Galilei (1597) was the inventor of the first thermometer-thermoscope. Galileo's thermoscope was a 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 of water. After some time, the air in the ball cooled, its pressure decreased, and the water, under the influence of atmospheric pressure, rose up the tube to a certain height. Subsequently, with warming, the air pressure in the ball increased, and the water level in the tube decreased, and when cooled, it increased.

With the help of a thermoscope, it was possible to judge only about the change in the degree of heating of bodies: it did not show numerical values ​​of temperature, since it did not have a scale. modern shape(having soldered the tube and turned it upside down) the thermometer was given by Gabriel Daniel Fahrenheit, a Dutch physicist, glass blower. And the constant (reference) points - boiling water and melting ice - were placed on the thermometer scale by the Swedish astronomer and physicist Anders Celsius in 1742.

Currently, there are many types of thermometers: digital, electronic, infrared, pyrometers, bimetallic, remote, electrocontact, liquid, thermoelectric, gas, resistance thermometers, etc. Each thermometer has its own principle of operation and its own scope. Let's consider some of them.

3.1. Liquid thermometers.

Liquid thermometers use the thermal expansion of liquids. Depending on the temperature range in which the thermometer is to serve, it is filled with mercury, ethyl alcohol or other liquids.

Liquid thermometers filled with mercury are used for accurate temperature measurements (up to a tenth of a degree) in laboratories. Alcohol-filled thermometers are used in meteorology to measure temperatures below -38° (since mercury solidifies at lower temperatures).

Alcohol thermometer.

3.2. Gas thermometers.

gas thermometer- a temperature measuring device based on Charles's law *.

Principle of operation: At the beginning of the XVIII century. In 1703, Charles established that the same heating of any gas leads to the same increase in pressure, if the volume remains constant. When the temperature changes on the Celsius scale, the dependence of gas pressure at a constant volume is expressed by a linear law. And from this it follows that the gas pressure (at V = const) can be taken as a quantitative measure of temperature. By connecting the vessel containing the gas to a manometer and calibrating the device, it is possible to measure the temperature according to the manometer readings**.

Within a wide range of changes in gas concentrations and temperatures and low pressures, the temperature coefficient of pressure of different gases is approximately the same, so the method of measuring temperature with a gas thermometer turns out to be little dependent on the properties of a particular substance used in the thermometer as a working fluid. The most accurate results are obtained if hydrogen or helium is used as the working fluid.

*Charles' law or Gay-Lussac's second law - one of the main gas laws describing the relationship between pressure and temperature for ideal gas. The formulation of Charles' law is as follows: for a given mass of gas, the ratio of gas pressure to its temperature is constant if the volume of the gas does not change. This dependence is mathematically written as follows: P/T=const if V=const and m=const.

**Manometer(Greek manos - rare, loose, sparse + other Greek μέτρον - measure, meter) - a device that measures the pressure of a liquid or gas.

3.3. Mechanical thermometers.

Mechanical thermometers operate on the same principle as liquid thermometers, but a spiral made of metal or bimetal is usually used as a sensor - two metal strips with different abilities to elongate with temperature changes, fastened with rivets. Mechanical thermometers are used to measure the temperature of liquids and gases in heating and sanitary installations, in air conditioning and ventilation systems, as well as to measure the temperature of loose and viscous media (for example, dough or glaze) in the food industry.

3.4 Optical thermometers.

Optical thermometers (pyrometers) allow you to register the temperature due to a change in the luminosity or emission spectrum of bodies. Optical thermometers are used to measure the surface temperature of objects in hard-to-reach (and hot) places.

3.5. Electric thermometers.

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

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

The most accurate and stable over time are resistance thermometers based on platinum wire or platinum sputtering on ceramics. The most common 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 4th degree equation at negative ones (the corresponding constants are very small, and in the first approximation this dependence can be considered linear). Temperature range -200 - +850 °C

*Electrical resistance- a physical quantity that characterizes the properties of a conductor to prevent the passage of electric current and is equal to the ratio of the voltage at the ends of the conductor to the strength of the current flowing through it.

**Thermocouple(thermoelectric converter) - a device used to measure temperature in industry, scientific research, medicine, in automation systems.

4. Tasks.

1. Determine the root mean square velocity of oxygen and argon molecules in air at 20°C.

2. At what temperature is the thermal velocity of nitrogen molecules equal to 90 km/h?

An experience Galileo.

Conclusion.

In conclusion, we examined the concept of temperature from a physical point of view, but it can also be considered as a vital factor for a person.

For example: for a person who is not connected with physics, temperature is a measure of the gradation of our sensations of heat and cold; at the household level, temperature is perceived as a parameter that serves to quantitatively describe the degree of heating of a material object.

In this project, several types of temperature

scales: Kelvin, Réaumur, Celsius, Fahrenheit, Rankine. Each scale has its own characteristics and shortcomings.

Some types of thermometers were also affected in the project: liquid,

gas, mechanical, optical, electrical. Each thermometer has its own principle of operation and its own scope.

We solved problems using the mean square velocity formula.

Conducted the experiment of Galileo, associated with a change in temperature. Created by Makarov and Stepanov

REPORT ON PHYSICS

TEMPERATURE SCALES, THERMOMETERS

AND THEIR INVENTORS

temperature scales. There are several graduated temperature scales, and the freezing and boiling points of water are usually taken as reference points. Now the most common in the world is the Celsius scale. In 1742, the Swedish astronomer Anders Celsius proposed a 100-degree thermometer scale, in which 0 degrees is the boiling point of water at normal atmospheric pressure, and 100 degrees is the melting temperature of ice. The division of the scale is 1/100 of this difference. When thermometers began to be used, it turned out to be more convenient to swap 0 and 100 degrees. It is possible that Carl Linnaeus took part in this (he taught medicine and natural science at the same Uppsala University, where Celsius taught astronomy), who back in 1838 suggested taking the melting point of ice as 0 temperature, but, it seems, did not think of the second reference point. To date, the Celsius scale has changed somewhat: 0 ° C is still taken as the melting temperature of ice at normal pressure, which is not very dependent on pressure. But the boiling point of water at atmospheric pressure is now equal to 99.975 ° C, which does not affect the measurement accuracy of almost all thermometers, except for special precision ones. The temperature scales of Fahrenheit, Kelvin, Reaumur, etc. are also known. The Fahrenheit temperature scale (in the second version, adopted since 1714) has three fixed points: 0 ° corresponded to the temperature of a mixture of water, ice and ammonia, 96 ° - body temperature healthy person(under the arm or in the mouth). As a control temperature for the comparison of various thermometers, the value of 32 ° for the melting point of ice was taken. The Fahrenheit scale is widely used in English-speaking countries, but it is hardly used in scientific literature. To convert Celsius temperature (С) to Fahrenheit temperature (F), there is a formula F = (9/5)C + 32, and for reverse conversion - the formula C = (5/9)(F 32). Both scales - both Fahrenheit and Celsius - are very inconvenient when conducting experiments in conditions where the temperature drops below the freezing point of water and is expressed negative number. For such cases, absolute temperature scales were introduced, which are based on extrapolation to the so-called absolute zero - the point at which molecular motion should stop. One of them is called the Rankin scale, and the other is called the absolute thermodynamic scale; temperatures are measured in degrees Rankine (Rа) and kelvins (K). Both scales start at absolute zero, and the freezing point of water corresponds to 491.7 R and 273.16 K. The number of degrees and kelvins between the freezing and boiling points of water on the Celsius scale and the absolute thermodynamic scale is the same and equal to 100; for the Fahrenheit and Rankine scales, it is also the same, but equal to 180. Celsius degrees are converted to kelvins using the formula K \u003d C + 273.16, and degrees Fahrenheit are converted to Rankine degrees using the formula R \u003d F + 459.7. In Europe, the Réaumur scale, introduced in 1730 by Rene Antoine de Réaumur, was widespread for a long time. It is built not in an arbitrary way, like the Fahrenheit scale, but in accordance with the thermal expansion of alcohol (with respect to 1000:1080). 1 degree Réaumur is equal to 1/80 of the temperature interval between the melting points of ice (0°R) and the boiling points of water (80°R), i.e. 1°R = 1.25°C, 1°C = 0.8°R., but is currently out of use.

After the introduction of the International System of Units (SI), two temperature scales are recommended for use. The first scale is thermodynamic, which does not depend on the properties of the substance used (working fluid) and is introduced through the Carnot cycle. The unit of temperature in this temperature scale is one kelvin (1 K) - one of the basic units in the SI system. This unit is named after the English physicist William Thomson (Lord Kelvin), who developed this scale and kept the value of the temperature unit the same as in the Celsius temperature scale. The second recommended temperature scale is the international practical one. This scale has 11 reference points - the phase transition temperatures of a number of pure substances, and the values ​​of these temperature points are constantly updated. The unit of temperature in the international practical scale is also 1 K.

At present, the main reference point of both the thermodynamic scale and the international practical temperature scale is the triple point of water. This point corresponds to strictly defined values ​​of temperature and pressure, at which water can simultaneously exist in solid, liquid and gaseous states. Moreover, if the state of a thermodynamic system is determined only by the values ​​of temperature and pressure, then there can be only one triple point. In the SI system, the temperature of the triple point of water is taken to be 273.16 K at a pressure of 609 Pa.

In addition to setting reference points determined using a temperature standard, it is necessary to choose a thermodynamic property of the body, which is described by a physical quantity, the change of which is a sign of temperature change or a thermometric sign. This property should be quite easily reproducible, and the physical quantity should be easily measurable. The measurement of the specified physical quantity makes it possible to obtain a set of temperature points (and their corresponding temperature values) intermediate with respect to the reference points.

The ratio of the temperature scale Fahrenheit and Celsius

Fahrenheit scale Celsius scale

Boiling point 212° 100°

Freezing point 32° 0°

Absolute zero temperature -459.67° -273.15°

When converting from Fahrenheit to Celsius, subtract 32 from the original number and multiply by 5/9.

When converting from the Celsius scale to the Fahrenheit scale, the original figure is multiplied by 9/5 and 32 is added.

Thermometers. The decisive contribution to the development of the design of thermometers was made by the German Gabriel Daniel Fahrenheit. In 1709 he invented the alcohol thermometer, and in 1714 the mercury thermometer. He gave them the same form that is used today. The success of his thermometers is to be found in his new method of purifying mercury; in addition, before sealing, he boiled the liquid in the tube.

René Antoine de Réaumur disapproved of the use of mercury in thermometers due to the small expansion coefficient of mercury. In 1730, he proposed the use of alcohol in thermometers, a. In 1731 he invented the water-alcohol thermometer. And since Reaumur found that the alcohol he used, mixed in a ratio of 5: 1 with water, expands in a ratio of 1000: 1080 when the temperature changes from the freezing point to the boiling point of water, he proposed a scale from 0 to 80 °.

Scientists. Anders Celsius. Anders Celsius was born on November 27, 1701 in Sweden. His area of ​​interest: astronomy, general physics, geophysics.

He taught astronomy at Uppsala University, founded an astronomical observatory there.

Celsius was the first to measure the brightness of stars, establishing the relationship between the northern lights and fluctuations in the Earth's magnetic field.

He took part in the Lapland expedition of 1736-1737 to measure the meridian. Upon his return from the polar regions, Celsius began active work on the organization and construction of an astronomical observatory in Uppsala and in 1740 became its director. Anders Celsius died on March 25, 1744.

The mineral Celsian, a variety of barium feldspar, is named after him.

Gabriel Fahrenheit. Daniel Gabriel Fahrenheit (1686-1736) German physicist. Born May 24, 1686 in Danzig (now Gdansk, Poland). Studied physics in Germany, Holland and England. He lived almost all his life in Holland, where he was engaged in the manufacture of precise meteorological instruments. In 1709 he made an alcohol, in 1714 - a mercury thermometer, using a new method of purifying mercury. For mercury thermometer Fahrenheit built a scale with three reference points: 0 ° corresponded to the temperature of the mixture of water - ice - ammonia, 96 ° - to the body temperature of a healthy person, and 32 ° was taken as the reference temperature for the melting point of ice. The boiling point of pure water on the Fahrenheit scale was 212°. The Fahrenheit scale is used in many English-speaking countries, although it is gradually giving way to the Celsius scale. In addition to making thermometers, Fahrenheit also improved barometers and hygrometers. He also studied the dependence of the change in the boiling point of a liquid on atmospheric pressure and the content of salts in it, discovered the phenomenon of supercooling of water, compiled tables specific gravity tel. Fahrenheit died in The Hague on September 16, 1736.

Rene Reaumur. Rene Antoin de Reaumur (Rene Antoin de Reaumur) was born on February 28, 1683 in La Rochelle, French naturalist, foreign honorary member of the St. Petersburg Academy of Sciences (1737). Works on regeneration, physiology, biology of insect colonies. He proposed a temperature scale named after him. He improved some methods of steel preparation, he was one of the first who made attempts to scientifically substantiate some casting processes, wrote the work "The Art of Turning Iron into Steel". He came to the valuable conclusion that iron, steel, cast iron, differ in the amount of a certain impurity, and by adding this impurity to iron, Réaumur obtained steel by carburizing or fusion with cast iron. In 1814, K. Careten proved that this impurity is carbon.

Réaumur gave a method for preparing frosted glass.

Today memory associates his name only with the invention of the long-used temperature scale. In fact, René Antoine Ferchant de Reaumur, who lived in 1683-1757, mainly in Paris, belonged to those scientists whose universality in our time - a time of narrow specialization - is difficult to imagine. Réaumur was at the same time a technician, physicist and naturalist. He gained great fame outside of France as an entomologist. AT last years In his life, Réaumur came to the idea that the search for the mysterious transforming power should be carried out in those places where its manifestation is most obvious - during the transformation of food in the body, i.e. while assimilating it.

William Rankin. William John McQuorn Rankin (Rankine) (1820-72), Scottish engineer and physicist, one of the creators of technical thermodynamics. He proposed a theoretical steam engine cycle (Rankin cycle), a temperature scale (Rankin scale), the zero of which coincides with the zero of the thermodynamic temperature, and in size 1 deg R. (°R) is equal to 5/9 K (the scale was not widely used).