Duhring sees latent heat as coming to his rescue. But, again, it only reflects his own lack of knowledge. If we take the examples set out above, of the transfer of mechanical energy, an amount of energy used to raise the ball at one end of the Newton's Cradle, is released, in equal amount, when the ball drops and strikes the next ball, and so on on, until the last ball rises. In similar manner, if a certain amount of heat is applied to a given quantity of water, raising its temperature, the energy is then stored in the water, and could be, in turn, transferred to something else, in equal measure. But, Duhring points out that, in turning water to steam, given a boiling point of 100⁰ C, more than 100⁰ C of heat is required, and a similar thing occurs when water is frozen, or ice turned to water.
Science, again, provided the answer to this apparent conundrum, and, again, it involves quantity being transformed into quality. When heat is applied to water, the water gets hotter, in equal amount. This heat consists of the water molecules moving around faster, as is the case with all matter. But, when water turns to steam, this represents not just a quantitative change in its temperature, but a qualitative change in its form/state. Now, rather than water molecules simply vibrating at a faster pace, the bonds that hold them together are broken, and the breaking of the bonds itself requires additional energy. The additional energy is latent heat.
“If, the steam is again transformed into water, by cooling and the water, in its turn, into ice, the same quantity of heat as was previously tied up is now again set free, i.e., is perceptible and measurable as heat. This liberation of heat on the condensation of steam and the freezing of water is the reason why steam is only gradually transformed into water, when cooled to 100°, and why a mass of water at freezing point temperature is only very gradually transformed into ice.” (p 78)
In other words, the heat energy has not simply disappeared, but has been used to do work, in the form of loosening the bonds between molecules. When those bonds are restored, as the steam becomes water, that energy is once more released.
“Now it is clear that the individual molecules of a body are endowed with far greater energy in the gaseous state than they are in the fluid state, and in the fluid state likewise than in the solid state. The tied-up heat has, therefore, not disappeared, it has merely been transformed, and has assumed the form of molecular tension.” ( p 79)
It is why we have steam engines rather than hot water engines, for example. But, a similar principle is involved in Einstein's equation E = MC2, except that the energy released, here, is not the result of that required to hold molecules to each other, but that released when the atom itself is split.
At the time Engels was writing, the theory of heat energy was itself only a hypothesis, because “as yet no one has ever seen a molecule, let alone one in vibration. For this very reason, like the whole theory which is still very young, it is certain to be full of defects but it can at least explain what happens without in any way coming into conflict with the indestructibility and uncreatability of motion, and it can even account in a precise way for the whereabouts of heat during its transformation.” (p 79-80)
But the development of the electron microscope did enable confirmation of the hypothesis and was able to observe the vibration of molecules. Later discoveries, however, throw into question the other specific aspects of Engels' account of the creation of the Earth and other rocky planets out of gaseous clouds, as described by Kant. This is certainly the origin of stars, and gas giants like Jupiter, but the latest theories suggest that the rocky planets, like, Earth, Mars Venus, etc., were created from the slow coming together of dust particles, under the influence of gravity as they circled the Sun. These dust particles are, themselves, the product of the previous explosions of stars in the earlier development of the universe, and which resulted in the creation of the heavier elements such as iron, gold and so on, which were seeded across the universe.
“Thus the difficulty about which Herr Dühring mumbles mysteriously does not exist, and even if we may come up against defects and gaps in applying the theory cosmically — defects and gaps which are due to our imperfect means of knowledge — we nowhere come up against theoretically insuperable obstacles. Here too the bridge from the static to the dynamic is the external impulse — the cooling or heating brought about by other bodies acting on the object which is in a state of equilibrium. The further we explore this natural philosophy of Dühring's, the more impossible appear all attempts to explain motion out of immobility or to find the bridge over which the purely static, the resting, can by itself pass to the dynamic, to motion.” (p 80-81)
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