374 On some of the Conditions of Molecular Action. 



But there is probably more than one influence at work in the 

 case of certain of the oxidations by catalysis which are effected 

 by the aid of metallic oxides and heat. From the accounts of 

 the process given by Mr. Eyre Ashby* and Dr. Henry f, it ap- 

 pears most probable that the heat by which the action is started 

 drives off from the pulverulent oxide all stain or taint of foreign 

 vapour, and leaves its particles free to exercise their molecular 

 energy, and to draw closely to them the vapours freshly sub- 

 mitted to them. In certain cases the approach is so close that 

 the chemical affinity of the organic vapour for oxygen overcomes 

 that of the metal, and redaction of the oxide and oxidation 

 of the vapour take place simultaneously. In the case of silver 

 this accident only increases the energy of the operation, probably 

 from the well-known attraction of silver for oxygen ; but with 

 most other metals (e. g. cadmium) the action is not carried on 

 until the nascent metal has attracted fresh oxygen from the air, 

 and nascent oxide is again ready to carry on the catalytic process. 



It is evident, however, that even in these cases, although che- 

 mical actions are going on in the catalyte, yet the purely mole- 

 cular force plays an important part in producing the result. 



I have been led to make these few and imperfect observations 

 upon a difficult and obscure subject, chiefly because I believe that 

 it is only by a careful study of molecular physics that we can 

 hope to gain any great advance in our knowledge of the working 

 of organic life. In biology we have to deal for the most part, 

 not with ordinary chemical processes or affinities, but with sub- 

 stances whose chemical reactions are continually modified by va- 

 riations in their molecular condition J. By the study of the phy- 

 sical relations of these bodies, we may hope, in time, to understand 

 something of the various forms of material which enter into or- 

 ganized structures, and to discover the mode in which, by certain 

 arrangements of their particles, potential energy can be stored 

 up ready to be given out when required. We may also in the 

 same direction learn a little of the, at present, mysterious working 

 of those bodies called ferments, which are so active in the living 

 body. It seems probable at least that amongst the numerous 

 forces at work in the living frame, and coordinated and governed 

 by the principle of life, we must rank the molecular energies of 

 various materials continually supplied in a nascent and active 

 condition ; and thus the study of their physical properties may 

 perhaps be permitted to find a place even in purely physiological 

 researches. 



* Phil. Mag. S. 4. vol. x. p. 52. 

 t Ibid. S. 3. May 1835. 



X See paper "On the Physiological Relations of Colloid Substances,'' 

 by the author, in the British Medical Journal, February 3, 1866. 



