DISCOVERY OF CORPUSCLES. 53 



4 



the positive charge on the plate decreased as the tempera- 

 ture rose above a certain point. It was obviously because 

 at a certain temperature negative particles began to be 

 evolved as well as positive, and that, flying side by side 

 with the positive particles from the wire to the plate, they 

 tended to neutralize their effect. Thus, a low temperature 

 and a high pressure are favorable to the production of posi- 

 tive ions ; and, conversely, a high temperature and a low 

 pressure are favorable to the production of negative ions. 



These negative particles, or ions, owing to the impor- 

 tance they have developed, are given a special name. They 

 are called corpuscles. } 



