316 History of Luminescence 



tion of the eyes and was, in fact, later retracted. He also analysed 

 the Bolognian stone which he regarded as a kind of talc and found 

 sulphur as an alkaline salt, and what he thought was mercury. His 

 drawings of the stone are shown in figure 33. Marsigli's language 

 was decidedly flowery. In the introduction to his book, there is a 

 passage which expresses his dissatisfaction with current explanations 

 of the light emission. 



Many have already written on my phosphorus, and perhaps they have 

 not done anything but give birth to so many little serpents of Egypt,^^ 

 to which may also be added mine; which is perhaps of a redder nature 

 than the others. Therefore I pray to Heaven that a destroying serpent 

 may appear as soon as possible; that is a great mind, which will further 

 illuminate [i. e., explain] the light of my phosphorus, a light as dark to 

 the mind's eye as it is clear to the eye of vision, despite all that which 

 has been written in the past. 



As we have seen in Chapter IV, the Bolognian stone was pre- 

 served in museums in Italy and considerable space devoted to its 

 history in the books of Lodovico Moscardo (1656, 1672) , Lorenzo 

 Legati (1677), and Paolo Boccone (1684). Paolo Casati (1617- 

 1707) in De Igne (1688) discoursed on phosphors of various kinds, 

 but in Domenico Bottoni's Pyrologia Typographia (1692) they are 

 merely mentioned in connection with fires that light but are not hot. 



GERMAN INTEREST 



In Germany, interest centered on the German phosphors, the 

 Baldeweinian and the phosphorus of mine, but an accotint of the 

 Bononian stone was published by Friedrich Hoffman, senior (died 

 1675) , a physician in Halle, father of the Friedrich Hoffman (1660- 

 1742) who was physician to Frederick I of Prussia and who dis- 

 covered the calcium sulphide phosphor in 1700. In Clavis Pharma- 

 ceutica Schroderiana (Halle, 1675) , Hoffman, senior, devoted over 

 a page to Lapis Bononiensis, " sponge of the sun, sponge of the 

 moon, holder of the heavenly light, luminous stone, lucifer, phos- 

 phorus, etc.," citing Potier, Liceti, Kircher, and Mazotta as authori- 

 ties for his account of the appearance, composition and methods of 

 preparation. Hoffmann stated that " although this stone [after 

 processing] is of external use in medicine— a lixivium for a depil- 

 latory is made from it— its outstanding quality is the delight pre- 

 sented to the eye." In contrast to the early use of the element 

 phosphorus as pills for the ailing, the Bononian phosphor gained no 

 reputation as an internal medicine, at least this use is not stressed 



^® Little serpents of ignorance. 



