134 Prof. J. G. MacGreo-or on Contact- Acti 



-- 



on 



weights from 60 to 150, and the value of m'v 2, is generally 

 about 20 : with the last three substances in the table, 

 where the molecular weights are high, 314 to 430 (taking 

 the calculated values m f ), m'v 2 is much larger, namely over 

 30 ; while dextrin, tannin, and amylodextrin show still larger, 

 and, taken in their order, increasing molecular weights, and 

 also larger and increasing values for m'v 2 . Thus it would 

 appear that with higher molecular weights the rate of diffusion 

 is abnormallv large. 



The exceptionally large values for mv l in the case of tne 

 weakest solution of cane-sugar is remarkable, but in the 

 absence of a duplicate determination it is well not to lay 

 much stress upon it. 



XVI. Contact- Action and the Conservation of Energy. 

 By Prof. J. G. MacGkegok, M.A., Sc.D* 



SEVERAL years ago Prof. 0. J. Lodge, in a series of 

 papers published in this Magazine t, proposed new 

 definitions of work done and energy, and claimed (1) that 

 by their aid he had deduced from the third law of motion 

 and the hypothesis of universal contact-action alone, a law 

 (which he called the law) of the conservation of energy ; 

 (2) that the law thus deduced was an extension of, and fully 

 as axiomatic as, the law ordinarily enunciated under the same 

 name ; (3) that action at a distance might be shown to be 

 incompatible with Xewton's third law, or the law of the con- 

 servation of energy, or both • and (4) that energy cannot be 

 transferred without being transformed, or transformed without 

 being transferred. These claims, though prima facie so 

 extraordinary as necessarily to have drawn attention, have 

 never, so far as I am aware, been seriously challenged, and it 

 is, perhaps, somewhat late in the day to challenge them now; 

 but the remarkable progress which has recently been made 

 in the application of contact-action theories > seems to make 

 it desirable that they should be subjected to examination. 



(1) The Deduction of the Conservation of Energy. 



In the first version of the argument by which this deduction 

 is made J, Prof. Lodge seems to me (a) to assume the ordinary 

 law of the conservation of energy in addition to the third law 



* Communicated bv the Author. 



f Phil. Mag. [5] vols. viii. (1879) p. 277, xi. (1881) pp. 36 & 529, xix. 

 (1885) p. 482. 



+ Ibid, vol. viii. (1879) p. 278. 



