The Experiments of Ramsay 



earth's crust. From these bodies have been 

 extracted a considerable, and even yet an un- 

 determined number of metals : thorium, cerium, 

 lanthanium, didymium, yttrium. In 1842 

 Mosander demonstrated that the last of these 

 metals consists in reality of three distinct bodies, 

 yttrium proper, terbium and erbium ; since then 

 the unremitting work of numerous chemists has 

 further extracted from the same bodies the new 

 elements, scandium, ytterbium, holmium, gado- 

 linium, to which should perhaps be added 

 thulium, neo-erbium, neo-holmium, dysprosium* 

 All these bodies, whose properties are so nearly 

 identical that their separation is barely possible, 

 come to lengthen the already long list of 

 elements. This remarkable similarity, and their 

 association in the same minerals, suggests the 

 inference of a common origin; this consideration 

 led the physicist, Crookes, to his celebrated theory 

 of meta-elements. 



Crookes attributes the evolution of the various 

 elements to the progressive condensation of a 

 single primitive matter, but the cooling of 



1 Quite recently M. Urbain succeeded in splitting ytterbium 

 into two elements neo-ytterbium and lutecium. 

 D 69 



