The Seventeenth Century 121 



One more phosphorus was soon to be added. Although the light 

 which appears on rubbing or breaking sugar was a common obser- 

 vation, the first material with this property to be prepared arti- 

 ficially was Homberg's phosphorus, an impure calcium chloride 

 discovered by Wilhelm Homberg (1652-1715) in 1693. The ma- 

 terial luminesced on scratching and striking and helped to found 

 the subject of triboluminescence. 



These discoveries emphasize the many ways in which light can 

 be produced and quite naturally became the basis for later classi- 

 fication of luminescences. Together with the existence of shining 

 flesh, fish, and wood, the burning of the sea and the many examples 

 of animal light, they served to confuse and complicate all attempts 

 to explain the cause of the light in universal terms. Indeed Bartho- 

 lin's idea of light as a fifth principle or element, equivalent to earth, 

 water, air, and fire, was becoming a more and more logical concept. 

 Light did appear to be present in all things and to manifest itself 

 in various ways. 



Textbooks of Chemistry and Physics 



It is rather surprising to find practically no mention of lumines- 

 cence in the early books on chemistry, even in those published after 

 the Bolognian phosphor was discovered in 1603. The Tyrocinium 

 Chymiciim of Jean Beguin (fl. seventeenth century) first appeared 

 in 1608 and passed through many editions and translations, but 

 there is nothing on phosphors in the 1625 edition, although calcina- 

 tion is discussed. 



The more detailed chemistries, Oswald Croll's *^ Bazilica Chymica 



(1608) , Nicolas le Febure's (died 1674) Traicte de la Chymie 



(Paris, 1660) , P. Thibaut's Cours de Chymie (Paris, 1667) , and 



Christolphe Glaser's Traite de la Chymie (Paris, 1673) to mention 



a few, were all published before the first edition of Nicolas Lemery's 



(1645-1715) Cours de Chymie (Paris, 1675) . Again, none of these 



books discuss luminescences, and in fact a treatment does not appear 



in the first or subsequent editions of Lemery until the fifth, which 



was translated into English in 1686 by Walter Harris. Lemery's 



later views on luminescence are extensive and will be found near 



the end of this chapter. 



The first textbook of physics in the modern sense is more difficult 



"Oswald Croll {ca. 1580-1609) wrote the original Basilica chymica in 1609. Some 

 eighteen editions of Croll's book appeared before 1658. The English edition, Bazilica 

 chymica et praxis chyyniatricae or royal and practical chymistry englished by a lover 

 of chymistry (London, 1670) , deals mostly with drugs and also contains nothing on 

 luminescence. 



