146 LIFE AND EXPERIENCES CHAP. 



weights which are yet essentially different substances. 

 To clinch matters, it was therefore necessary to show 

 that the gas obtained by the combustion of the 

 Kimberley diamonds gave the well-known spectrum 

 obtained by burning diamonds from other sources and 

 other forms of carbon. This Schuster and I accom- 

 plished ; the spectrum of the South African carbon 

 dioxide was identical with that yielded by other 

 varieties of carbon. 



I do not know that much of my other experimental 

 work is of more than purely chemical interest. I may, 

 however, say that I determined the vapour densities of 

 the chlorides of thallium and lead, proving that each of 

 these compounds contained one atom of the metal. I 

 also discovered the existence of two chlorides of the 

 metals tungsten and uranium, which had theoretically 

 no business to exist ; but they insisted upon it, and 

 WC1 5 and UC1 5 , though of anomalous composition, 

 still maintain their individuality. Besides proving the 

 existence of compounds which have no right to be 

 there, I succeeded in disproving the existence of a 

 so-called element. This was termed phillippium, and 

 was the only one which at that time had no place in the 

 periodic system, and I showed that it was a mixture of 

 two others, terbium and yttrium. 



The accurate determination of the spectrum of these 

 rarer earth elements was a matter of importance, and 

 Schuster and I mapped that of the pure terbium salts 

 which I had prepared in the foregoing experiments. 



During this period my students were also active, and 

 many researches in their names appeared in the 

 scientific journals of those years. 



On October Qth, 1872, I distributed the prizes to the 

 Liverpool Operatives' Science Classes, my subject 

 being the scientific education of the working man. 



