The Middle Ages 53 



diamond would glow when warmed in water. The statement seems 

 possible, as certain varieties of diamond are thermoluminescent. 

 However, E. Becquerel (1867: 12) has pointed out that Albertus 

 did not speak of placing the diamond in hot water but in " clear 

 and limpid water "— " emicat in tenebris superfusa aqua clara et 

 limpida in vase nigio mundo et polito." Like other early reports of 

 luminous stones, the actual emission of light is doubtful. 



Miscellaneous References to Luminescence 



Knowledge of luminous phenomena ^^ during the Middle Ages 

 was sketchy and the beliefs fantastic. The marvel was characteristic 

 of the age. Marcellin Berthelot -^ (1829-1907) has found manu- 

 scripts, transcribed in the thirteenth and fifteenth centuries, con- 

 taining an old Greek description of a method of making a carbuncle 

 glow at night by coloring it with the " bile " of marine animals, 

 whose entrails, scales, and bones luminesce. Among the directions in 

 the book of marvels, De Mirabilis Mundi,^^ which might imply a 

 knowledge of luminescence were: "How to write letters that can 

 be seen only at Night," and " How to make oneself seem on fire 

 from head to foot." The book also contained receipts for Greek 

 fire ^° and many other things. 



^■^ The only mention of luminescence or phosphorescence in the index to George 

 Sarton's (1931) great work, An introduction to the history of science, in which the 

 first two volumes treat knowledge of nature before 1300, has to do with Mark the 

 Greek (second half of the thirteenth century) . In addition to Greek fire, pyrotechnic 

 and explosive recipes in his Liber igninm, phosphorescent substances, also described 

 by M. Berthelot, are mentioned as Mark the Greek's invention. In the third volume 

 (1947: 531) which covers the fourteenth century, there is a statement regarding the 

 Gascon Franciscan theologian. Vital du Four (or Dufour, died 1327) , living at 

 Montpelier in 1295-1296, who, " In his commentary on the Sentences [a dictionary of 

 Biblical ethics, written about 1305] showed an interest in such natural phenomena as 

 magnetic attraction and phosphorescence." The phosphorescence was a " liquor 

 liquidus " prepared from fireflies (see Chapter III) . The six-volume History of 

 magic and experimental science of Lynn Thorndike, covering the first sixteen cen- 

 turies A. D., contains practically nothing on luminescence. Vol. 1 and 2 appeared in 

 1923, vols. 3 and 4 in 1934 and vols. 5 and 6 in 1941. 



2^ M. Berthelot, Collection des anciens alchemists grec 3:336-338, Paris, 1887-1888, 

 and Ann. de Chem. et Physique (6th Ser.) 14: 429-32, 1888. 



^^ Usually attributed to Albertus Magnus. See Lynn Thorndike History of magic 

 and experiinental science 2: 737, 1923. 



="* Greek fire was not a luminescence. The origin is explained by Guido Panciroli 

 (1523-1599) , whose book, Rerum 7nemorabilium, etc. (Ambergae, 1590) , was trans- 

 lated into English as The History of many memorable things lost, which were in use 

 among the ancients: etc. (London, 1715) . Chapter XIX is devoted to " Greek Fire 

 commonly call'd Wild-Fire." In the reign of Constantinus Pogonatus (the bearded 

 Constantine) the " Art to Kindle Fire under Water " was discovered and called Greek 

 Fire because the inventor was Callinicus, a Greek, in a. d. 680. Constantine defended 

 himself against this fire in a battle with the Saracens. 



Others say Marcus Graecus invented Greek Fire, a mixture alleged to be made up 



