THE TRANSFORMATION OF ELEMENTS 235 



presence. Further work has shown that lithium exists very 

 widely in minute traces, and that it is very difficult to free salt 

 solutions from its presence completely. All that can be stated 

 at present is that in the actual experiments just described 

 lithium was certainly detected in the "treated" solution, and 

 was not detected in an " untreated " solution otherwise identical. 



In August 1908 Mme. Curie and Mile. Gleditsch published 

 an account of experiments devised especially to test the supposed 

 copper-lithium transmutation. They found that when pure 

 water was allowed to stand in contact with glass, the dissolved 

 salts contained lithium. On this account the whole of their 

 work was carried out in platinum vessels. They used a solution 

 of copper sulphate fractionally recrystallised a large number of 

 times to free it from lithium. The quantities of copper sulphate 

 and of radium emanation employed were comparable to those 

 used in Ramsay and Cameron's experiments ; no lithium was 

 detected in the solution after treatment, moreover the weights 

 of the alkali residues from "treated " and " untreated " solutions 

 did not differ distinctly. The authors conclude that the trans- 

 mutation of copper into lithium and sodium cannot be held as 

 established. It is evident that much further work is necessary 

 before the matter can be decided definitely. 



It will be observed that the changes of which indication has 

 been found follow the periodic system strictly. The emanation, 

 the highest member of the argon series, breaks down into 

 helium, and under certain conditions into neon, and perhaps 

 argon. Copper, when subjected to the same forces, possibly 

 gives lithium, and also sodium. In this connection it is 

 desirable to bear in mind that the spectroscope, on which this 

 evidence is based, allows the detection of smaller amounts of 

 matter than any other known method except the measurement 

 of radioactivity. Ramsay and Cameron, by comparison with 

 known mixtures of lithium and sodium, estimated the amount 

 of lithium obtained from about a gram of copper nitrate as 

 o - oooi7 milligram. Mile. Gleditsch, in work which will be re- 

 ferred to in the next section, has estimated that it is possible to 

 detect spectroscopically one part of lithium in 10,000 of sodium. 



With a sufficiently small spectrum tube it is easy to 

 detect spectroscopically amounts of the rare gases of the 

 order of o - i cubic millimetre. (Perhaps considerably less can 

 be detected.) Such a volume in the case of neon weighs o'oooi 



