38 Mr, William Croohes [Feb. 18, 



The law of Prout, and still more the better established and far- 

 reaching periodic law of Newlands (since developed by Professors 

 Mendeleeff, Meyer, and Carnelley), seem to presuppose the existence 

 of a genetic relation among the elements. 



Philosophers in the present as in the past, — men who certainly 

 have not worked in the laboratory, — have reached the same view from 

 another side. Thus Mr. Herbert Spencer records his conviction that 

 *' the chemical atoms are produced from the true or physical atoms 

 by processes of evolution under conditions which chemistry has not 

 yet been able to produce." 



And the poet has forestalled the philosopher. Milton (' Paradise 

 Lost,' Book V.) makes his Archangel Eaphael say to Adam, instinct 

 with the evolutionary idea, that the Almighty had created 



♦' one first matter all. 

 Indued with various forms, various degrees 

 Of substance." 



If we can show how the so-called chemical elements might have 

 been generated we shall be able to fill up a formidable gap in our 

 knowledge of the universe. We have a preponderance of cumulative 

 evidence to prove that both heavenly bodies and living organisms 

 have been formed by evolution. We are seeking now to extend this 

 law to the so-called elements, to the first principles of which stars 

 and organisms alike consist. 



If we survey the distribution of the chemical elements we find 

 two very distinct cases. On the one hand we see bodies grouped 

 in definite proportions with other bodies from which they differ 

 exceedingly and to which they are held by affinity, more or less 

 strong. To obtain either of two such bodies in a separate state, that 

 affinity, as every student of chemistry knows, must be overcome. 

 Instances of such association are too common and abundant to need 

 mention. In such cases each of the bodies grouped together has fairly 

 marked properties. One of them, moreover, for the most part has an 

 atomic weight very different from that of the other. 



In the second case we find bodies associated with other bodies 

 more or less closely allied to themselves. They are not held together 

 by any decided affinity; they are not combined in definite propor- 

 tions, and their atomic weights are often almost identical. If we 

 wish to obtain one or more of these bodies in a separate state, the 

 difficulty encountered lies not in the strength of the affinities to be 

 overcome but in the circumstance that whatever reagent we emjiloy 

 acts upon one of the substances in nearly the same manner as it does 

 upon the other. Hence, to obtain one body of this kind- entirely 

 separate is an exceedingly tedious and difficult task. Nay, we are 

 sometimes at a loss to decide whether we have before us a really 

 simple body or a mixture of bodies whose properties are almost 

 identical. 



The most striking instance of such association is found in the 



