IX THE LAST HALF- CENTURY. 61 



oretically, at any rate, the transmutability 

 of the elements is a verifiable scientific 

 hypothesis ; and such inquiries as those 

 which have been set afoot, into the possi- 

 ble dissociative action of the great heat of 

 the sun upon our elements, are not only 

 legitimate, but are likely to yield results 

 which, whether affirmative or negative, 

 will be of great importance. The idea 

 that atoms are absolutely ingenerable and 

 immutable ' manufactured articles ' stands 

 on the same sort of foundation as the idea 

 that biological species are ' manufactured 

 articles ' stood thirty years ago ; and the 

 supposed constancy of the elementary 

 atoms, during the enormous lapse of time 

 measured by the existence of our uni- 

 verse, is of no more weight against the 

 possibility of change in them, in the in- 

 finity of antecedent time, than the con- 

 stancy of species in Egypt, since the days 

 of Rameses or Cheops, is evidence of their 

 immutability during all past epochs of 



