ON THE PHYSICAL VIEW OF NATUKE. 



185 



may succeed in doing this consistently seems at present 

 uncertain. It has been maintained that the very 

 elements of all physical measurement, the independ- 

 ence of the three dimensions in space, necessitates us 

 to supplement the energy-conception which by itself 

 includes no more reference to direction than the con- 

 ception of mass by an assumption of a purely mechani- 

 cal nature such as the number of degrees of freedom, 

 and that the much-discussed correlation of all forms of 

 energy, as it is suggested by W. Gibbs's formulae, cannot 

 be usefully carried farther. This correlation l has been 



and Clausius. The latter method 

 grew out of the gradual application 

 of thermo - dynamics to chemical 

 phenomena, where the mechanical 

 treatment had turned out to be 

 powerless. This more ambitious 

 scheme of remodelling the whole 

 of physics, chemistry, and me- 

 chanics on the model of the 

 classical thermo - dynamics dates 

 from the year 1887, when Prof. 

 Qeorg Helm published his first 

 treatise ('Die Lehre von der En- 

 ergie,' Leipzig) and revived the 

 word " energetics " invented by 

 Rankine. Subsequently he pub- 

 lished his application to chemistry 

 ('Grundziige der mathematischen 

 Chemie,' Leipzig, 1894), very 

 much under the influence of 

 Willard Gibbs's studies of chem- 

 ical equilibria and Duhem's elab- 

 oration of Helmholtz's conception 

 of free energy. His last work 

 (' Die Energetik,' Leipzig, 1898) 

 gives a history of the gradual 

 purification of the energy concep- 

 tion from mechanical admixtures, 

 into which all earlier writers on 

 the subject except Lord Kelvin 

 are shown to have lapsed, and 

 attempts a reconstruction of me- 

 chanics on " energetic " principles, 

 defending the author's position 



against various criticisms which 

 had meantime been made. 



1 The great generalisation of the 

 science of energetics referred to in 

 the text was first explicitly put 

 forth by Helm in his treatise of 

 1887. He himself holds that he 

 there finally brought together sug- 

 gestions made in various ways by 

 Zeuner (1866), Mach (1871), Gibbs 

 (1875), Maxwell (1875), Von Oettin- 

 gen (1885), and Popper (1884), and 

 expressed them in the form of a 

 general principle. The two factors 

 into which all energy can be sep- 

 arated are called by various sub- 

 sequent writers intensity, potential 

 level on the one side; extensity, 

 capacity, weight, on the other. 

 In spite of further expositions of 

 Helm in 1890 the subject did not 

 attract much attention till Prof. 

 Ostwald introduced it in a slightly 

 modified form in the second edition 

 of his great work on physical chem- 

 istry (1893), making it the founda- 

 tion of the doctrine of affinity. 

 He had evidently, between the 

 first and second editions, given up 

 the mechanical for the "ener- 

 getic " treatment of the subject 

 (see, inter alia, note 2, p. 114, 

 of the 2nd edition ; vol. ii. p. 12). 

 At the meeting of the German 



