INTENSITY OF MAGNETIC AND DIAMAGNETIC FORCES. 7^7 



To give some idea of the temperature of the bismuth, I may 

 mention, that in the fourth weighing the metal in a fluid state 

 escaped from the interior through the sohdifying upper crust ; 

 that the temperature after the tenth weighing was judged to be at 

 158° F. to 176° F., after the eleventh at about 131° F., and after 

 the last at about 104° to 113° F. After this last weighing I 

 satisfied myself merely that the attraction remained constant, or 

 at least did not vary 5 milligrms. 



65. Hence it is indisputably certain, that the diamagnetism 

 of bismuth diminishes as the temperature increases. This dimi- 

 nution is considerable. During the experiment described, the 

 intensity of the diamagnetism, which on the contrary increases 

 as the temperature diminishes, was augmented sixfold. 



If we suppose that during its cooling the bismuth becomes 

 oxidized, and thus increases in weight, or that some magnetic 

 body (iron), the magnetism of which increases as it cools, remains 

 mixed with it, both of these causes would affect the result ob- 

 tained, so as to augment the increase of the intensity of the 

 diamagnetism of the bismuth. 



The above result is especially remarkable, because by it 

 the hypothesis that magnetism and diamagnetism when once 

 called into action are an identical excitement of matter, is sup- 



• The cu)) moved from the halves of the keeper when weights had not been 

 placed in immediately before. When the attraction was diminishing, an ob- 

 servation of tliis kind would be most accurate, if the su])position, that an unob- 

 served concussion might have caused the separation, had not arisen. 



