70 History of Luminescence 



chief books on this subject until near the end of the seventeenth 

 century. 



Luminous Stones 



In his book on luminous things, De Lunariis, Gesner first cited 

 Aelian on the luminous stone brought by a stork to Heracleis, and 

 then wrote: " The solans is a stone, which is called the eye of the 

 sun. It has a shape like the pupil of the eye, from which light shines. 

 The carbuncle likewise shines at night with a ruddy glow, as Mar- 

 silio Ficino ^'^ writes." 



This belief in linriinous jewels seems to have become universal 

 in medieval times. -^ Hildegard, wife of Theodoric, Count of Hoi- 

 land, presented to the Abbey of Egmund a " chrysolampis," which 

 shone so greatly at night that the monks were alleged to be able 

 to read without any other light. In Sir John Mandeville's (1300?- 

 1377) travels there is an account of an emperor of Cathay who 

 " hathe in his chambre, in on of the pyleres of gold, a Rubye and 

 a Charboncle of half a fote long, that in the nyghte semethe so grete, 

 clartee, and shynynge, that it is als light as day." Like other Mande- 

 ville stories this is no doubt a fable, although it has been frequently 

 repeated. 



More credible is the story of Gesner regarding Catharine of 

 Aragon (1485-1536) , Queen of England, who wore a ring set with 

 a stone which luminesced at night. Gesner thought it was a ruby, 

 but a diamond seems more probable, as certain varieties are phos- 

 phorescent. Benvenuto Cellini (1500-1571) , sculptor and worker 

 in gold, in his treatise on jewelry (Due Trattati dell' Orificera, 1568) 

 told of a diamond which shone after exposure to light, and the 

 experiments of Robert Boyle (see Chap. X) leave no doubt of 

 the truth of Cellini's statement. 



Another story of the same period concerning a luminous stone 

 that could not be touched without danger was related by the French 

 historian, J. A. de Thou (1553-1617). This stone was brought from 

 the East Indies and presented to Henry II, King of France, on the 

 occasion of his entry into the town of Bologna in 1550. John Jonston 

 (1632) stated that it had a " wonderful shape and nature, for it 

 shown with light and clearness exceedingly, and it seemed as if it 

 were all on fire, and turn it which way you would, the lustre of it 

 so enlightened the ayre with its beams, that they could hardly endure 

 to look upon it." 



2« The Italian philosopher and scholar (1433-1499) , president of the Platonic 

 Academy in Florence. 



2' See C. W. King, The natural history of precious stones, 237 ff., London, 1870, and 

 G. F. Kunz, The curious lore of precious stones, Chap. V, Philadelphia, 1913. 



