Manchester Memoirs, Vol. xlviii. (1904), No. 8. 25 



The discovery of radium by Mme. Curie, and its 

 preparation on a commercial scale by Herr Giesel, afforded 

 the opportunity of putting the view to direct experimental 

 test. The activity of radium is of the order of a million- 

 fold greater than that of uranium or thorium, and the 

 element must therefore be disintegrating a million times 

 more rapidly. Radium, as will be deduced later, is itself 

 probably of the nature of a slow-changing transition-form, 

 which results from the disintegration of one of the heavier 

 elements present in pitchblende, and the philosophical 

 way of regarding the research, is to consider the radium 

 employed as representing the equivalent quantity of 

 mineral. Thus the quantity of material investigated could 

 be made very large and the second of the two possible 

 methods described became available. The experiments 

 were carried out last summer by Sir William Ramsay and 

 myself Although the quantities of radium we were able to 

 employ were only small, viz , in two succeeding experiments, 

 20 and 30 milligrams respectively, they each represent the 

 essential portion of at least a hundred kilograms of the 

 original mineral. At the time of making the experiments 

 they had been allowed to remain some months in the dry 

 solid state, and it was assumed for the reason mentioned that 

 the helium produced during that time would accumulate 

 in the solid and be liberated when it was dissolved. The 

 gases obtained in this manner were freed from the hydrogen 

 and oxygen which are always present, through the decom- 

 position of the water of crystallisation which occurs (Giesel), 

 by means of a glowing spiral of partially oxidised copper 

 wire. They were then forced through a capillary U-tube 

 immersed in liquid air to condense the emanation and an}- 

 carbon dioxide present, into a spectrum tube of exces- 

 sively small volume. Practically the complete spectrum 

 of helium was obtained. The proof of the continuous 



