18 THE ALUMNI JOURNAL 



in some cases thousands of smaller particles, the most important 

 of which are termed Electrons. 



Radioactivity, as the term indicates, is that property of a sub- 

 stance which causes it to resolve itself into more simple or ultimate 

 particles, by the process of emanation or radiation from the sub- 

 stance, of particles of matter so small that the comparative size of 

 the atom passes into significance. 



For a good mental picture of the atomic condition or state of these 

 radioactive substances, we must conceive that their atoms are in 

 a constant process of disintegration, or we might say spontaneous 

 decomposition. This decomposition takes place very slowly as 

 compared with the amount of force or energy displayed. 



Passing on now in our line of thought, we say that there eman- 

 ates or issues forth from the atoms of these radioactive substances, 

 three distinct kinds of emanations, called respectively the Alpha, 

 Beta and Gamma rays, which differ from each other in several 

 characteristics. Now the question arises, wherein lies the cause of 

 this disintegration, and what are the main dift'erences between the 

 rays resulting from it? It is now mainly accepted that an atom of 

 anything is that quantity of matter, which when further decompos- 

 able is resolved into particles charged with positive electricity, and 

 those charged with negative electricity, these being associated to- 

 gether in the atom, and by the terrific disturbance set up resulting 

 in the separation of these positive and negative particles, there is 

 formed the third emanation or ray, which is believed to be an 

 ethereal pulsation or X-ray. The flying positive particles constitute 

 the Alpha ray, the negative particles the Beta ray, and the Ethereal 

 pulsation the Gamma ray. According to the most recent theories, 

 it is believed that all elements are made up of a definite and un- 

 changing number of positive particles, without regard to whether 

 it is one element or another; they are all identical so far as the 

 number of positive particles is concerned. But as to the number of 

 negative particles, they vary exceedingly for the different elements, 

 and it is believed that herein lies the cause of the difference in phy- 

 sical and chemical properties, atomic, weights, etc. In fact, it is 

 the number of negative particles to the atom which gives to the 

 elements their individuality. 



