62 Master Minds of Modern Science 



kinds of rays, which are called alpha-, beta-, and gamma- 

 rays. In the chapter on Sir Ernest Rutherford's work we 

 shall tell of the use he has made of alpha-rays for break- 

 ing up atoms. They were alpha-rays that burned M. 

 Becquerel. Beta-rays have quite a different action. 

 They increase growth, and it has been found that plants 

 can be stimulated by these beta-rays into a most amazing 

 luxuriance. 



Of one hundred rays given out by radium ninety are 

 alpha-rays, nine are beta-rays, while only one is a gamma- 

 ray, yet these gamma-rays are the most wonderful of the 

 three. It has been discovered that they travel with the 

 velocity of light — that is, in round numbers, at a speed of 

 one hundred and eighty-five thousand miles a second — 

 and that they have a tremendous power of penetration. A 

 sheet of paper will cut off the alpha-rays, a sheet of tinfoil 

 will stop the beta, but the gamma will penetrate half an 

 inch of solid steel, and it is these gamma-rays that have 

 such a marvellous effect upon what are called malignant 

 growths. 



Perhaps the most astonishing thing is that they have 

 what is termed a selective quality. They pass through 

 healthy tissue, leaving it unharmed, and only attack the 

 diseased tissue. We do not know the cause of cancer, 

 whether it is a germ or a parasite or a poison, but what- 

 ever it is the gamma-rays of radium will attack it, break 

 it down, and in many cases effect a complete cure. Very 

 large doses of gamma-rays can be used without harming 

 the patient, but the difficulty is that there is not nearly 

 enough radium chloride in existence for the purpose for 

 which it is so sadly needed. 



And this brings us back to what is really the subject of 

 our chapter, the beginnings of radium. Pierre Curie, the 

 son of a Parisian doctor, was born in the year 1859. His 

 father was a remarkable man. Instead of bringing up his 

 sons on the usual conventional lines he encouraged them 



