168 CHEMICAL DISCOVERY AND INVENTION 



run too far in advance of positive knowledge is not good physical 

 philosophy. The difficulties of investigation in this field, how- 

 ever, are likely not to diminish but rather to multiply. This is 

 partly due to the excessively minute quantities of matter which 

 have in some cases to be dealt with. An illustration of this 

 occurs in connection with the chemical action of the rays from 

 radium. Thus water is decomposed with production of oxygen, 

 hydrogen peroxide, and hydrogen gas, and it has long been 

 known that the glass of tubes containing the salts of radio-active 

 elements becomes discoloured, assuming a purplish tint after a 

 time, and this appears to be due to the liberation of sodium or 

 potassium or possibly some other element contained in the 

 ingredients of the glass. 



These observations led not unnaturally to the idea that under 

 the influence of electrons from radio-active matter some of the 

 common elements might be broken up into fragments so that, 

 for example, copper might be degraded into sodium and lithium. 

 Experiments announcing this change were published, but other 

 chemists could not get the same result, and at the present time 

 the general opinion would not be in favour of such a conclusion. 



Somewhat similarly it has been asserted by Professor Collie 

 and Mr. Patterson that the cathode rays are capable of pro- 

 ducing helium and neon out of gases and other matters in which 

 they are believed not to exist as such, that is to say, by dis- 

 integration of one kind of atom other kinds are produced. But 

 the same effects are not always producible even by the original 

 observers, and by others are altogether denied. In such cases 

 there is no alternative but to " wait and see." 



THE AGE OF THE EARTH 



A very interesting question has been raised which, though not 

 definitely chemical in its character, may be mentioned here in 

 consequence of its connection with the study of the properties 

 and distribution of radium and other radio-active substances. 

 It relates to estimates concerning the probable age of the earth. 



The earth was once a hot fluid mass which is supposed to 

 have resulted with the sun and planets from the condensation of 

 nebulous matter. The question arises how long is it since the globe 

 of the earth assumed approximately the condition in which it now 

 exists, since the solidification of the crust and the separation of 



