Phosphorescence 317 



by any of the writers of the seventeenth or eighteenth century. They 

 were carried away by the novelty of something which could capture 

 and hold the light of heavenly bodies. 



NICOLAS LEMERY AND FRENCH OPINION 



In France as in England, little was known of the Bononian stone 

 in the 1660's and 1670's and the secret of preparation was also sup- 

 posed to have been lost. This statement is made in the fifth edi- 

 tion of Lemery's Cours de Chymie in 1686, which contains methods 

 of preparing the phosphorus of urine and the Baldeweinian phos- 

 phorus, but no details regarding the Bononian phosphorus. In 

 the meantime Wilhelm Homberg (1652-1715), the physician and 

 chemist, born in Batavia of German parents, whose later life was 

 spent in Paris, journeyed to Italy expressly to inquire about the 

 stone. Although many in Bologna toward the end of the century 

 were also unaware of the methods of preparation, Homberg was 

 successful in his quest. He imparted the information to Lemery 

 and showed him many experiments, recorded in detail in the eighth 

 edition ^° of Cours de Chymie. Like Cellio, he drew figures on wood 

 or paper with white of €:gg, dusted the moist egg-white with the 

 powdered phosphor and allowed the material to dry. By exposure 

 to light, luminescent pictures could be made, similar to those pre- 

 pared today.-^ 



It is important to note that Lemery held that the crushing of the 

 Bononian stone must be done in a brazen mortar in order to have 

 success in preparing the phosphor. An iron mortar was particularly 

 bad, as grinding in iron led to products which did not shine at all. 

 Marble, porphyry or crystal mortars were also not good. These 

 observations were actually made by Homberg, whose many experi- 

 ments dealing with preparation of phosphors were not well known 

 to his contemporaries.-- Although presented to the French Academy 

 of Science in 1673, the volume for the years 1686-1699 did not appear 

 until 1730. Homberg also found that too long grinding of the 

 Bononian stone in a bronze mortar also gave poor results. To 

 Homberg, therefore, must be attributed the observation that traces 

 of impurities (from the bronze) greatly affect the light-emitting 



^°The English translation by James Keill appeared in 1698. 



^^ The use for phosphorescent paintings was described by Marsigli (1698) and 

 Homberg may have learned of it from him. 



^-In Homberg's (1730) article, " Nouveau phosphore," presented in 1693, two kinds 

 of phosphors were recognized— one, made from blood or urine, luminesced day and 

 night, without being kindled (the element phosphorus) , the other kind needed to be 

 exposed " au grand jour," such as the Bolognian and Baldewinian phosphors. 



