CHAPTER IV. 

 THE TESTING OF THE LAW. 



When once the weight of the atom of an element is known 

 the properties of the element are fixed. There is a fatality 

 about it. 



How true this is may be aptly illustrated. Turn to the 

 table of the law (Fig. 5) and note in Group III the third 

 and fourth elements, Sc (Scandium) and Ga (Gallium), and 

 in the fourth group the fourth element Ge (Germanium). 

 When Mendeleeff enunciated his law and made his table 

 originally, he found it necessary, in order to make the table 

 true, to leave these three spaces vacant for undiscovered 

 elements, and, not content with this, he proceeded in 1871, 

 on the basis of the law, to predict the properties which these 

 elements should possess when discovered. 



Think of the presumption of it, that out of the seventy- 

 eight odd substances of which God had made his universe, 



S*~^ ' N 



three were missing ! And that these three possessed proper- 

 ties which he proceeded to specify with extreme minute- 

 ness. These three hypothetical elements he named eka- 

 boron, eka-aluminum, and eka-silicon, "little imagining," 

 as he says himself, ' ' that he would live to see the verifica- 

 tion of his predictions." 



But so it was; for out of the night of the unknown, one 

 after another came to meet him. One from the hills of 

 Scandinavia, another from the Pyrenees of France and 

 a third from the mines of Germany. The three elements 

 were named scandium, gallium and germanium, and they are 

 (34) 



