172 History of Luminescence 



Probably the most famous of the books on physics -^ in the early 

 eighteenth century was Pieter van Musschenbroek's (1692-1761) 

 Elementa Physicae. Van Musschenbroek visited England in 1717 

 and, like 'sGravesande, was much influenced by Newton's work. 

 Later he also became professor of mathematics and natural philoso- 

 phy at the University of Leyden and famous for association with 

 the discovery of the Leyden jar. The first edition of his text ap- 

 peared in Latin in 1734 and a two volume translation. Elements of 

 Natural Philosophy, was made by John Colson in 1744, from which 

 the following extracts are taken. French editions of his works 

 appeared in 1751 and 1769. 



A considerable amount of chemistry is included, for van Mus- 

 schenbroek was greatly concerned with the nature of " fire," a 

 word he used in a very broad sense. His thesis appears to have been 

 that if enough " fire " were present in a body, and if the fire were 

 in motion, the body would shine. This reasoning was applied to 

 luminescences as well as to incandescent matter. Van Musschen- 

 broek cited the experience of himself and of others which indicated 

 that many metals increase in weight when burned and hence " Fire 

 which thus copiously insinuates itself into bodies, and adheres to 

 them, is found to increase their weight, and therefore like all other 

 bodies is itself endued with gravity." 



He then continued: 



A large quantity of fire, when pent up within the parts of bodies, very 

 often shines, as may be seen in the Helvetian androdamas, in the Bono- 

 nian stone, and almost in all other stones, whether calcined, or first dis- 

 solved in acid spirits, and afterwards calcined; as also in boles [tree- 

 trunks], earths, the bones of animals, the ashes of plants. For all these 

 things, being something illuminated by the sun, and then carried into 

 an obscure place, will shine and retain the light for some time; nay, 

 if they lose it, being again exposed to the sun, they will recover it again. 

 The Bononian stone, being preserved in cotton, keeps it's shining virtue 

 above five years. The calcined belemnites and the topaz do the same. . . . 

 Bodies endued with the property of imbibing light may lose the same 

 by frequent ignitions, as is observed in crystals, the phosphorus stone of 

 Bern, and emeralds. There are others which acquire that faculty by 

 ignition, as the Bononian stone, the belemnites, gypse, the phosphorus of 

 Balduin. 



Fire is susceptible of very different degrees of velocity, continually 

 decreasing before it passes from that most rapid motion, which it enjoyed 



-« Additional early texts on natural philosophy were those of John Keill (1720) , 

 Benjainin Worster (1730), Richard Helshain (1739), and John Rowning (1737-1744), 

 but they contained nothing on luminescence except for a rather extended account of 

 the aurora borealis by Rowning. 



