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Mikhail Vasilyevich Lomonosov - Meditations on the Cause of Heat and Cold  [from On the Corpuscular Theory]; Translated, with an Introduction, by Henry M. Leicester [Professor of Biochemistry]; Harvard University Press, Cambridge, Massachusetts, 1970

.....We consider  three possible ways that internal motion might occur:

1) if insensible particles continuously change places, or

2) if they rotate while remaining in place, or

3) if they  continuously move backward and forward in an insensible  space and in an insensible period of time.

The first we consider as progressive, the second as rotary, and the third as oscillatory internal motion. Now we must consider which of these motions produces heat…..

………….Thus, after this [allthe arguments], as we have rejected progressive and oscillatory internal motions, it necessarily follows that heat consists in internal rotary motion (6) of the cohering material (4);………….

…… consider the main effects observed in hot bodies. It is clear from considering these that

1) in bodies the heat is greater the more dense is the cohering of their material and vice versa. Thus, looser tow burns with greater flames but gives much less heat than that which burns after denser packing. Straw which under ordinary conditions burns with a light flame is used by the inhabitants of the fertile parts of Russia which lack wood in place of firewood, after they have first fastened it into a thick, compact bundle; when more porous wood is burned, it gives less heat than denser wood, and coal which contains rocky material in its pores produces a stronger heat than wood charcoal which, like a sponge, has empty spaces. Moreover, air of the lower atmosphere, which is denser than air of the higher atmosphere, heats bodies around which it flows more than the latter, as is indicated by very warm valleys surrounded by mountains covered with perpetual ice;

2) denser bodies also contain more cohering material in the same volume than does flowing material. Since it is well known from the laws of mechanics that the amount of motion is the more considerable, the greater the amount of material found in motion, and vice versa, then if a sufficient basis for heat consisted in the internal motion of the flowing material, the more rarefied body in whose pores was a greater supply of flowing material should have a greater capacity for heat than denser bodies. However, since on the contrary the amount of heat rather corresponds to the amount of cohering material of the body, therefore it is evident that a sufficient cause for heat consists in the internal motion of the cohering material of the body.

This truth is confirmed by the action of celestial fire directed on a body by a burning glass: on its removal from the focus this fire remains in it longer the denser it is, so that in the most rarefied of bodies, air, it does not last for the shortest perceptible time.

Hence we add that heat is different according to the differing heaviness and hardness of the body, and experiment shows that its intensity is proportional to the weight of the body, corresponding to the degree of cohesion of its particles, evidently an indication that the cohering material of the body is the material of its heat.