228 SCIENCE PROGRESS 



insoluble substance, resolvable into two parts, one resembling 

 platinum, but differing considerably in its chemical behaviour. 

 Gross assumes that platinum is decomposed into a new metal ; 

 to regard this as a " modification " is an unjustifiable extension 

 of that term. His results await confirmation. 



The most convenient source of a relatively enormous amount 

 of energy, which can be set free locally, and allowed to act 

 on the molecules and even the atoms of different substances, 

 is unquestionably radium emanation. The enormous store of 

 energy liberated as each particle disintegrates has been men- 

 tioned. When this is liberated in water, the water is decom- 

 posed ; an account of this, and of the effect on various gases, 

 has been given in Part II. (p. 82). The changes there discussed 

 are molecular. It is now necessary to consider what proofs have 

 been put forward for atomic changes produced by this agency. 



From the fact that radium emanation decomposes water into 

 hydrogen and oxygen, Sir William Ramsay was led to try its 

 effect on a solution of copper sulphate, with the idea that there 

 would result a deposit of copper equivalent to the hydrogen. 

 That such an idea was justifiable is proved by his results with 

 silver solutions, as yet uncompleted, in which a deposit of 

 silver is actually formed, while oxygen is liberated, along 

 with only a very small quantity of hydrogen. In the case 

 of the copper solution, however, no copper was deposited, 

 but on analysing the solution a trace of lithium was observed 

 spectroscopically. Such a result was quite unlooked for. The 

 copper sulphate was prepared from the ordinary pure salt, 

 recrystallised four times. Laboratory copper sulphate invariably 

 contains lithium, but it has been found that after such a series 

 of crystallisations, the lithium is entirely eliminated. 



The experiment was repeated several times. On the second 

 occasion copper sulphate was prepared from pure copper elec- 

 trolytically deposited on platinum, and " contact " sulphuric 

 acid. The copper sulphide from this experiment was converted 

 into acetylide, and that into nitrate ; this was employed in a 

 third experiment. 



In all cases a trace of lithium was found after treatment with 

 emanation. This lithium might result in four ways— (a) as 

 impurity in the copper salt, (b) from the glass bulb in which the 

 experiment was carried out, set free either by action of the 

 emanation or of the salt solution, (c) as impurity in the reagents 



