RADIO-ACTIVITY i8i 



periods. But there are grave difficulties in the 

 use of radium, for we are as yet very ignorant of 

 its entire physiological action ; its after-effects on 

 those who have handled any large quantity for 

 some time are far from reassuring. 



The medicinal springs of Bath and Buxton 

 contain radio-active emanations, while radium 

 itself has been detected in the solid deposits at 

 Bath. It is possible that the curative effects of 

 these waters is caused by their radio-activity, and 

 if so, the uselessness of drinking the water, when 

 kept and removed to a distance, may be due, 

 more to the decay of the activity of the emana- 

 tions, than to the provident imagination of the 

 local authorities. 



In seeking an explanation of these physio- 

 logical effects, some experiments, due to Mr W. B. 

 Hardy, must be noticed. As we have seen in 

 Chapter V., solutions of salts and acids, which 

 are conductors of electricity, possess the power 

 of coagulating clear solutions of colloidal or jelly- 

 like substances such as albumen or sulphide of 

 arsenic, and this action is readily explained by 

 referring the coagulative action to the electric 

 charges on the ions. 



The influence of charged ions on colloidal 

 solutions being thus made clear, Hardy tried the 

 effect of exposing a very sensitive solution of 

 globulin, a substance contained in the living tissue 

 of animals, to the charged particles emitted from 

 radium, which produce ions so readily when pass- 

 ing through a gas. The penetrating /3 rays were 

 without action, but the easily absorbed a rays, 

 which enter a film of the liquid when it is placed 

 near a radium salt with no screen interposed, 



