106 EEPLIES TO CRITICISMS. 



being regarded as consequent on the combinations of tlic 

 various mechanically-determined, motions of their various 

 components. Without at all out- running, however, this pro 

 gress in the mechanical interpretation of molecular phe 

 nomena, it suffices to point out that the indispensable 

 elements in any chemical conception are units occupying 

 places in space, and exerting forces on one another. This, 

 then, is the common character of all these sciences which 

 we at present group under the names of Mechanics, 

 Physics, Chemistry. Leaving undiscussed the question 

 whether it is possible to conceive of force apart from ex 

 tended somethings exerting it, we may assert, as beyond 

 dispute, that if the conception of force be expelled, no 

 science of Mechanics, Physics, or Chemistry remains. Made 

 coherent, as these sciences are, by this bond of union, it is 

 impossible to thrust among them any other science without 

 breaking their continuity. We cannot place Logic between 

 Molar Mechanics and Molecular Mechanics. We cannot place 

 Mathematics between the group of propositions concerning 

 the behaviour of homogeneous molecules to one another, and 

 the group of propositions concerning the behaviour of hetero 

 geneous molecules to one another (which we call Chemistry). 

 Clearly these two sciences lie outside the coherent whole we 

 have contemplated : separated from it in some radical way. 



By what are they radically separated ? By the absence of 

 the conception of force. However true it may be that so 

 long as Logic and Mathematics have any terms at all, these 

 must be capable of affecting consciousness, and, by impli 

 cation, of exerting force ; yet it is the distinctive trait of 

 these sciences that not only do their propositions make no 

 reference to such force, but, as far as possible, they delibe 

 rately ignore it. Instead of being, as in all the other 

 sciences, an element that is not only recognized but vital ; in 

 Mathematics and Logic, force is an element that is not only 

 not vital, but is studiously not recognized. The terms in 



