60 SCIENCE PROGRESS 



Longmans) was acquired by the Laborator}^ in the interests of 

 the many users of radium in this country. 



Radium and the Geologist 



It was at one time supposed that all the elements would 

 prove to be radioactive in greater or lesser degree ; but the 

 trend of observation and experiment is that this property is 

 confined to relatively few elements. One piece of evidence 

 which has led to this result is to be found in Prof. Joly's 

 work on the pleochroic halos in certain kinds of mica. These 

 halos are seen as small coloured patches under the microscope, 

 and were long an object of mystery to the geologist. Joly has 

 recently shown, however, that the halos are due to coloration 

 of the mica by alpha rays expelled from a minute nucleus of 

 radioactive matter. But, at the same time, mica is found un- 

 altered and uncoloured when associated with large amounts 

 of other elements, a fact which seems to show that such elements 

 do not emit ionising rays even over geological epochs of time. 



Few would have ventured to prophesy ten years ago that 

 the new science would put an arresting finger on the estimates 

 of the longevity of the sun and the age of the earth — subjects 

 of exceptional interest both to the biologist and the geologist. 

 Yet, in the earth's crust, the amount of radioactive matter and, 

 with it, the quantity of heat spontaneously emitted far exceed 

 that which is necessary to reconcile the older physical estimate 

 of the earth's age — based on the earth's internal heat — with 

 the much longer period which geologists claim as necessary. 



Radium and the Physician 



If unshielded, radium carried in close proximity to the body 

 for any considerable time produces an ulcer that is extremely 

 difficult to cure. It would, on the contrary, be anticipated 

 that an agency possessing such vital characteristics would, like 

 X rays, find application in the treatment of disease. And, as 

 is well known, this has proved to be the case. It has resolved 

 itself now chiefly into a question of improving the technique 

 and finding the appropriate " dose." It is in this field of work 

 that, as I have stated above, Germany has so greatly exerted 

 herself. It is a field which is now receiving more attention in 



