Theoretical chemistry from the standpoint of Avogadro's rule & thermodynamics / [Walther Nernst].

  • Walther Nernst
Date:
1911
Catalogue details

Licence: In copyright

Credit: Theoretical chemistry from the standpoint of Avogadro's rule & thermodynamics / [Walther Nernst]. Source: Wellcome Collection.

    31/840 (page 7)
    But according to our experiments hitherto, the convertibility of matter is limited to certain conditions. The law of the indestructi- bility of matter furnishes the first limitation, viz. that in any event this change in physical property concerns only identical masses of the substances [i.e. that in the change there is neither gain nor loss of mass]. Further experience gained in this direction—the result of a vast amount of painstaking work of the chemical laboratory, from the attempts of the alchemists to change base metals into gold, to the wonderful syntheses performed by our organic chemists of the present—has brought the further knowledge that, in general, even identical masses of substances essentially different are not convertible into each other. Simple and Compound Matter.—Innumerable investigations, which have had for their object, on the one hand, to reduce compound matter into simpler by chemical analysis, and, on the other hand, to bring together different substances to make a new one by chemical synthesis, have led to the conviction that, in decomposing the substances occurring in nature, one always comes to a number of substances incapable of further decomposition, the so-called elementary bodies or elements; of these nearly eighty have been isolated. Every attempt at the further decomposition of these elementary bodies has thus far been fruitless;1 but from these elementary bodies can be made synthetically all the substances collectively known to us. Only those substances are convertible into each other which contain the same elements, and indeed each element in the same proportion. The Indestructibility of Energy. (The first law of thermo- dynamics).—Many fruitless attempts to find a perpetuum mobile—i.e. a machine which of itself is able to perform external work continuously, and to an unlimited degree,—have finally led to the conviction that such a thing is impossible, and that the fundamental notion of making such a machine is in opposition to some law of nature. This law of nature is stated in the following way :—If any selected system is subjected to a reversible process, i.e. if any series of changes whatsoever occur so that it finally returns to its original condition, then the external work A, performed by the system during the reversible process, is proportional to the amount of heat, W, absorbed at the same time, i.e. A = JW (a) The coefficient J, the mechanical equivalent of heat, is independent of the nature of the system selected, and its numerical value varies only with the 1 The phenomena of radio-activity, which will be described later, point certainly to a spontaneous decomposition of certain elements which is outside the influence of the experimenter.