66 The Diamond 



While direct evidence is lacking, an interesting observation may be 

 based on Pliny, which, it seems to me, is conclusive to some degree; and 

 this is the curious circumstance that Pliny is familiar with the magnetic 

 or electrical property of just those gems which have the best claim to 

 being identified with the stones luminous at night of the Chinese, — 

 tourmaline and diamond. In regard to the former (lychnis) he states 

 that these stones, when heated by the sun or rubbed by the fingers, 

 will attract chaff and scraps of papyrus. 1 As to the diamond, he 

 remarks that its hostility toward the magnet goes so far, that, when 

 placed near it, it will not allow of its attracting iron; or if the magnet 

 has already seized the iron, it will itself attract the metal and turn it 

 away from the magnet. 2 The fact is correct that diamond becomes 

 strongly electric on friction, so that it will pick up pieces of paper and 

 other light substances, though it is not a conductor of electricity, differ- 

 ing in this respect from graphite. 3 Whether the diamond, as asserted 

 by Pliny, can check the attractive power of the magnet, seems to be a 

 controversial point. Garcia ab Horto was the first to antagonize 

 Pliny's allegation, on the ground of many experiments made by him. 4 

 C. W. King 6 has the following observation: "This stone is highly 

 electric, attracting light substances when heated by friction, and, as 

 we have already noticed, 6 has the peculiarity of becoming phospho- 



1 Has sole excalf actas aut attritu digitorum paleas et chartarum fila ad se rapere 

 (xxxvn, 29, § 103). 



2 Adamas dissidet cum magnete in tantum, ut iuxta positus ferrum non patiatur 

 abstrahi aut, si admotus magnes adprehenderit, rapiat atque auferat (xxxvn, 15, 

 §61). 



* "All gems when rubbed upon cloth become, like glass, positively electrified. 

 Gems differ, however, in the length of time during which they will retain an electrical 

 charge. Thus tourmaline and topaz remain electric under favorable conditions for 

 several hours; but diamond loses its electricity within half an hour" (Farrington, 

 Gems and Gem Minerals, pp. 34, 70). The Arabs attribute to the garnet (bijddi) 

 the power of attracting wood and straw (J. Ruska, Steinbuch des Aristoteles, p. 144). 

 I do not believe with Ruska that this statement may be caused by confusing the 

 garnet with amber. Though Vullers and Steingass, in their Persian Dictionaries, 

 assign to the word bijddi or bejdd the meanings "garnet" and "amber," the latter 

 interpretation is evidently suggested by the reference to the attractive power. 



4 Ne meno e il vero che tolga la virtu alia calami ta di tirare il ferro; percioche 

 ne ho fatto io molte volte esperienza, e l'ho trovata favola (Italian edition of 1582, 

 p. 182). 



s Antique Gems, p. 71. 



6 In the passage referred to (p. 27) King says that "the property of phospho- 

 rescence is possessed by no other gem except the diamond, and this only retains it for 

 a few minutes after having been exposed to a hot sun and then immediately carried 

 into a dark room. This singular quality must often have attracted the notice of 

 Orientals on entering their gloomy chambers after exposure to their blazing sun, and 

 thus have afforded sufficient foundation to the wonderful tales built upon the simple 



