30 Clarke, The Atomic Theory. 



molecules, which may cohere, but cannot pass through 

 one another, and they preserve their individuality. 

 Possibly I may misapprehend this theory, for it has been 

 published in a most concise form, and the reasonintj upon 

 which it rests is not given in detail. I cannot criticise it, 

 but I may offer some suggestioii-s. If matter consists of 

 waves in a universal medium, how does chemical union 

 take place ? Shall we conceive of h)drogen as represented 

 by one set of waves and nitrogen by another, the two 

 differing only in amplitude ? If so, when they combine 

 to form ammonia there should be either a superposition 

 of one set upon the other, or else a complex system might 

 be found showing interference phenomena. But would 

 not the latter supposition imply a destruction of matter as 

 matter is defined by the theory ? Could one such wave 

 coalesce with or neutralise another? To conceive of a 

 union of waves without interference is not easy, but the 

 facts of chemical combination must be taken into account. 

 When we remember that compounds exist containing 

 hundreds of atoms within the molecule, we begin to 

 realise the difficulties which a complete theory of matter 

 must overcome. Chemical and physical evidence must be 

 taken together ; neither can solve the problem alone. At 

 present, the simplest conception for the mind to grasp is 

 that of an aggregation of particles. Beyond this all is 

 confusion, and mathematical devices can help us only a 

 little. In speaking thus I assign no limit to the revela- 

 tions of the future ; some theory, now before the world, 

 may prove its right to existence and survive ; but none 

 such, as yet, can be taken as definitely established. The 

 theory which stands the test of time will not be a figment 

 of the imagination ; it must be an expression of observed 

 realities. But enough of speculation ; let me, before I 

 close, say a few words of a more practical character. 



