DISTINCTION OF PROPERTY FROM FORCE. 213 



difference in size) that certain kinds have the capacity 

 for being pushed towards each other by the force of 

 chemical attraction. As I have said elsewhere, 1 * 



" Here also two distinct factors are involved, viz., the property 

 of chemical affinity on the one hand, and the force of chemical 

 attraction on the other, the product of these two being chemi- 

 cal combination. The act of chemical combination implies a 

 certain amount of motion, which, again, involves the expendi- 

 ture of something, and this something cannot be the inherent 

 property which constitutes the chemical relationship or affinity 

 between the combining bodies, because that property remains 

 undiminished and unchangeable. What is expended must, 

 therefore, here, as elsewhere, be force. The inherent property 

 in this case cannot, any more than in that of gravity, be in it- 

 self a power of attraction, but only determines the effect of the 

 acting force. This force is the same for all chemical combina- 

 tions, and is therefore called the force of chemical attraction, 

 just as we speak of the force of gravitation, but it is the pro- 

 perty of affinity which determines what particular bodies shall 

 combine with one another, using in the act of combination the 

 requisite amount of the common stock of force. No amount 

 of the force of chemical attraction will cause the combination 

 of bodies destitute of affinity for each other. To speak of the 

 force of chemical affinity already implies an hypothesis which 

 the foregoing considerations show to be erroneous. In strictly 

 accurate language, we should say every act of chemical com- 

 bination involves the existence of the property of chemical 

 affinity, and the expenditure of the force of chemical attrac- 

 tion. What the nature of this force of so-called attraction 

 may be, is not decided, but it probably is caused, like gravita- 

 tion, by pressure from without upon the particles of matter n 



(p. 99) "When we thus separate distinctly the 



ideas of property and force, and confine the latter to its strict 

 meaning in physics, we perceive the completely subordinate, 

 although still essential, part it plays. Force can have no power 



* " Life, and the Equivalence of Force," p. 98 and p. 189. 



