852 DMITRI IVANOVITSCH MENDELEEFF. 



Lecoq de Boisbaudran; of scandium, corresponding to eka-boron, by 

 Nilson; and of germanium, which proved to correspond in all respects 

 to eka-silicon, by Winkler. When, in 1871, I described to the 

 Russian Chemical Society the properties, clearly defined by the 

 periodic law, which such elements ought to possess, I never hoped that 

 I should live to mention their discovery to the Chemical Society of 

 Great Britain as a confirmation of the exactitude and the generality 

 of the periodic law. Now, that I have had the happiness of doing 

 so, I unhesitatingly say that although greatly enlarging our vision, even 

 now the periodic law needs further improvements in order that it may 

 become a trustworthy instrument in further discoveries." 



Since this time two hitherto unsuspected groups of elements have 

 been discovered and proved capable of inclusion within the Periodic 

 System: — the inert gases, affording a natural transition between the 

 halogens and the alkali metals ; and the radio-active elements, which for 

 the most part long defied classification, but which now, thanks to 

 Fajans and Soddy, constitute a further proof of the universality of the 

 law. His attempt to introduce into the system the hypothetical 

 element coronium with an atomic weight of 0.4, and the "ether" of 

 the physicist with the atomic weight of 0.000000000053 have scarcely 

 found acceptance, especially since Moseley's calculation of atomic 

 numbers has indicated that hydrogen has the smallest atomic weight 

 of any element. 



Two of his fundamental ideas in connection with the Periodic 

 System remain open to question: First, his repugnance to the doctrine 

 of the unity of matter; second, his contention that the elements, if 

 arranged periodically, must follow inexorably in the order of the atomic 

 weights. He lived to see many atomic weights revised so as to con- 

 form to this principle, and died with the conviction that tellurium, for 

 instance, must have a lower atomic weight than iodine. The dis- 

 covery of isotopy makes this outcome still a possibility. 



Mendeleeff, given up by the doctors to die at an early age, lived in 

 activity and usefulness to the age of seventy-three. The summer 

 before his death, weakened by influenza, he began to put his affairs 

 in order, but he retained his vigor of mind and his interest in current 

 events up to the last. The Orthodox Church, the Czar, and the 

 educational institutions of St. Petersburg rendered his memory ex- 

 traordinary honors as he was borne out to be laid beside his mother 

 and his favorite son. Count Witte well characterized his services 

 when he said : — " In him Russia lost her pride, the great scholar and 

 the upright patriot; industry lost its best adviser; the government a 



