Gaza. William Thomson

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In 1851 William Thomson (baron Calvin) (1824-1907) has suggested to use the thermometer in which as a working body air serves at constant pressure for realisation of an absolute scale of temperatures; on this scale it would be possible to calibrate other thermometers. Air has been chosen simply for convenience reasons; any another is suitable ' constant ' gas, but, of course, not near to its point ozhizhenija. (Thomson actually has gone further and has shown how to construct even more comprehensible scale on the basis of theory N. L.S.Karno (1796-1832) about ' to warmth motive power '.)

The Described events show that physics development full unexpectedness. Measurement of properties of gases has found out some surprising laws, and their more detailed studying has given a basis for construction of the scale comprehensible from the point of view of the theory. Thanks to it there was a possibility to make more exact measurements and to develop thermometry. It has allowed to measure factor of expansion of mercury as temperature function instead of accepting to its constants; as a result it was possible to make amendments to the results received earlier. So the physics, like a caterpillar, tightens itself forward.

In gas laws there is something even more important. Why in general they exist? After all there are no so universal laws of liquids or laws of firm bodies. The Simple fact of similarity in behaviour of various gases means that something essentially distinguishing them from liquids and firm bodies is inherent in gases. We know now that it is the nature of a gaseous state. Properties of firm bodies and liquids depend on type of particles of which they consist: forces of interaction between different atoms and molecules can differ in very wide limits.

In distance gases between molecules times are usually very great in comparison with the sizes of molecules, and, during which molecules approach so to affect against each other, are rather very small. Thus, gases possess the properties which are not dependent on forces with which molecules operate against each other. That is why all gases behave equally. However, when conditions vary, that is when pressure and temperature reach high values, the probability of collisions of molecules increases, and similarity in behaviour of various gases disappears.