176 



SCIENTIFIC THOUGHT. 



49. 



Ostwald's 

 ' Allgemeine 

 Chemie.' 



introducing thermo -dynamics into chemistry, after W. 

 Gibbs had shown how to look at chemical energy as a 

 sum of many forms of energy, and after Helmholtz had 

 more clearly defined the useful conception of free or 

 available energy as the measure of chemical reaction 

 that Prof. Ostwald at length ventured after the lapse of 

 eighty years to unite in a comprehensive doctrine the 

 scattered fragments of our existing knowledge regard- 

 ing chemical affinity. This he did as a restorer of the 

 forgotten labours and fame of Berthollet. 1 By the 



kinetic definition of temperature. 

 The two principal founders of 

 thermo - dynamics, Clausius and 

 Lord Kelvin, did not resort to 

 kinetic conceptions when estab- 

 lishing the two laws which deal 

 with the conservation and trans- 

 formation of energy : Rankine, 

 however, connected the subject 

 with his theory of molecular vor- 

 tices ; and Clausius, who was one 

 of the founders of the kinetic 

 theory of gases, very early at- 

 tempted to interpret the laws of 

 the transference of heat by the 

 help of that theory. So like- 

 wise did Maxwell, Helmholtz, 

 Boltzmann, and many others. 

 Mr Bryan, in a very valuable 

 report on the " Researches relat- 

 ing to the Connection of the 

 Second Law with Dynamical 

 Principles," has given a critical 

 summary of these various at- 

 tempts (see Brit. Assoc. Reports, 

 1891, p. 85). The three peculiar 

 forms of motion referred to in 

 our last chapter periodic, rota- 

 tional, and rapid translational (dis- 

 orderly) motion have been used to 

 suggest manifold means of trans- 

 lating thermo-dynamical processes 

 into kinetic models, explaining, 

 as Mr Bryan says, ' ' the second 

 law, about which we know some- 



thing, by means of molecules 

 about which we know much less " 

 (p. 121). It does not seem that 

 much more has been gained than 

 a general presumption that a 

 mechanical illustration is possible. 

 To the statistical ideas elaborated 

 mainly by Maxwell and Boltz- 

 mann I shall revert when treat- 

 ing generally of the statistical view 

 of nature. 



1 Prof. Ostwald has himself, in 

 the Inaugural Lecture which he 

 delivered on the occasion of his 

 accession to the chair of physical 

 chemistry at Leipzig, 23rd Nov- 

 ember 1887, given a very lucid 

 statement of the principles in- 

 volved. He goes back to the two 

 theories of chemical action repre- 

 sented at the beginning of the 

 century by Bergmann on the one 

 side and Berthollet on the other. 

 In place of the conflict of chemical 

 forces, in which the stronger ob- 

 tains a complete victory (complete 

 reactions) the view of Bergmann 

 Berthollet introduces the "mani- 

 fold play of forces acting to and fro, 

 the result being that every one gets 

 its due. The more powerful sub- 

 stance gets more, the weaker less. 

 Only in cases where one of the 

 possible compounds in consequence 

 of its properties entirely leaves 



