MKMOIH VIII.] THE PHOSPHORESCENCE OF BODIES. 133 



MEMOIR VIII. 



ON THE PHOSPHORESCENCE OF BODIES. 



From the Philosophical Magazine, Feb., 1851 ; Harper's New Monthly Magazine, 



No. 325. 



CONTENTS: Early observations on phosphorescence. The diamond. 

 Duration of shadows. Lemery's theory. Du Fay's theory. Quali- 

 ties of diamond and fluor-spar. The volume of a phosphorescent body 

 does not change during its glow. A structural change accompanies the 

 phosphorescence of bodies ; there is a minute disengagement of heat. 

 Phosphorescence is not communicable. Absolute quantity of light 

 emitted. 



THERE are some surfaces on which if a shadow falls, it 

 can be brought into view a long time subsequently. 



A belief in the existence of the carbuncle, a stone 

 supposed to have the property of shining in the dark, 

 appears to have been current from the very infancy 

 of chemistry. It gave rise to many legends among the 

 alchemists, and early travellers relate marvellous stories 

 respecting self-shining mountains and gems. Thus it 

 was said that the King of Pegu wore a carbuncle so 

 brilliant that if any of his subjects looked upon him in 

 the dark, his countenance seemed as though it was irra- 

 diated by the sun, and that in a certain part of North 

 America there was a mountain which illuminated the 

 country for many miles, and served by its rays to guide 

 the Indians at night. The story seems to indicate that 

 the locality of this wonder was somewhere in the west- 

 ern part of Pennsylvania. Mr. Boyle relates that a gov- 

 ernor of one of the American colonies imparted this fact 

 to him at a time when he was charged with the superin- 



