74 DIVISIBILITY OF MATTEK ATOMIC THEOKY. 



those derived from his later discovery of the chemical 

 reactions produced by light passing through compound 

 gases, concur with Mr. Graham's various researches 

 in pointing at a molecular mechanism, a definite 

 principle of embodiment of atomic figures, forces, 

 and motions, destined hereafter to become a special 

 department of science closely allied, however, to 

 chemistry by those principles of analysis, synthesis, 

 substitution, &c. which have so marvellously inter- 

 preted to us the intimate constitution of all compound 

 bodies. Chemists are still not agreed as to the best 

 mode of tabulating or symbolising the results which 

 enrich this part of their science. Of the schemes pro- 

 pounded (and four are now on the table before me) 

 each has its appropriate value. And in this very fact 

 we find evidence that they are but provisional, and 

 steps towards some perfect system even now looming be- 

 fore us and well-nigh certain of attainment. Founded 

 as it must be on strict numerical proportions, it will 

 probably disclose or suggest relations of atomic figure 

 also, as exponents of the combinations and changes 

 matter undergoes when thus reduced to the infinitesi- 

 mal parts in which all material action really resides. 



The future progress of this enquiry will doubtless 

 elucidate more completely the physical distinctions of 

 elementary atoms and molecules, both as to their nature 

 and effects in action. The present theoretical distinc- 

 tion is that best expressed by Wurtz in the words given 

 in the subjoined note. 1 This definition shows, what 



1 L'atome est la plus petite quantite d'un element qui puisse exister 

 dans un corps compose^ comme indivisible par des forces chimiques. 



