Chap. 2.] Bohgnian Pbofphorus. 183 



projected, they are found, by a variety of experiments, 

 to be fubject to the fame laws of ATTRACTION that' 

 govern all other bodies. ' On this principle the ma- 

 jority of phiiofophers have explained the phenomena 

 of the Bolognian flone, and what are called the folar 

 phofphqri. 



The difcovery of the Bolognian phofphorus, as re- 

 lated by Mr. Lemery, has already been detailed. The 

 property of imbibing and emitting light is not, how- 

 ever, confined to one fpecies, but is common to all 

 the varieties of that mineral, which is called ponderous 

 ipar. 



The light which they emit bears an analogy to that 

 which they have imbibed. In general, the illuminated 

 phofphorus is red ; but when a weak light has been 

 admitted to it, or when it has been received through 

 pieces of white paper, the emitted light is of a pale 

 white *. 



It has been already remarked f, that an artificial 

 phofphorus may be obtained from all fubflances which 

 can be reduced to a calx by burning only, or by folu- 

 tion in the nitrous acid. Some diamonds, however, as 

 well as emeralds and other precious ftones, are found 

 to have the fame property without any chemical pre- 

 paration ; and a diamond has been known to retain 

 its virtue of emitting light, after being buried in wax 

 fix hours J. In fact, Beccaria has obferved, that ai- 

 med all natural bodies have the power of imbibing 

 light, and of emitting it in the dark. To metals and 

 water, however, he could not communicate the flighted 

 degree of this property - } but he found that although 

 water in its fluid Hate could not be made to mine 



* Prieftley's Optics, p. 363, 364. | See Chap. i. 



4. Prieftley's Optics, p. 367. 



]Sf 4 fa 



