CHEMICAL ELEMENTS AND ATOMS URBAIN 213 



discoveries became so common tliat instead of names they attributed 

 provisory notation, be it to the bands or the supposed new element. 

 When they had used up the Latin alphabet recourse was had to the 

 Greek which in its turn would apparently fail. The rare earth ele- 

 ments came in swarms. They became no longer a group but a whole 

 fog. Finally, since a halt had to be made somewhere, Crookes pro- 

 nounced his famous aphorism, " a band, an element." 



The subject grew chaotic; but even this chaos was not sufficient. 

 Spark spectra were brought into the fray. Lecoq de Boisbaudran 

 exhausted the alphabet to z and Demarcay the capitals of the Greek 

 alphabet. Then the phosphorescent cathode added their quota 

 which again required the use of two alphabets. It took the bril- 

 liant imagination of Crookes to build upon his first beautiful dis- 

 covery the wonderful edifice of meta and ortho elements. Ortho 

 elements broke up into meta elements. The structure of clear ideas 

 so carefully built until then was in danger of shipwreck. The 

 yttria earths, with Crookes at the helm, were sucked into the 

 whirlpool along with samarium. His fertile imagination amalga- 

 mated the most bizarre ideas with those of a genius. Departing 

 from reasonable points of view, he compared spark spectra with 

 phosphorescent spectra. Experience later refused to justify the step 

 he then took in assuming that both spectra obeyed the same laws. 



Since spark spectra augment in intensity with the increase in con- 

 centration of an element he assumed that the same would happen 

 with phosphorescent spectra. His conviction was so strong that he 

 made no experimental trial to justify an analogy which to him 

 seemed evident. Further, while he was astonished at the sensitive- 

 ness of his cathode spectra, he did not note that that of the spark 

 spectra was very limited. Indeed, his technique in the case of spark 

 spectra differed little from that of Lecoq de Boisbaudran, which did 

 not permit the observation among the yttria earths of any but gado- 

 linium, dysprosium, ytterbium, and, of course, yttrium. In fact, 

 Crookes could observe only yttrium. The spebtrum appeared con- 

 stant to him, while he found great variations in the atomic weight. 

 From this he felt it right to assert that yttrium, an element as indi- 

 cated by its spectrum, had a variable atomic weight. He was not 

 the only one of this opinion. Greatly influenced by Hinrichs, who 

 criticised severely the work of J. S. Stas, the dogma of the constancy 

 of atomic weights singularly staggered in this period of equivoca- 

 tion. The various portions, in the fractionations of Crookes, iden- 

 tified by their spark spectra, differed in their phosphorescent spectra. 

 Therefore they were characterized by Crookes as distinctly different 

 atoms of the same element. They were called meta elements of 

 yttrium. 



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