310 History of Luminescence 



Montalbani ^ replied from Bologna, January 1, 1634: 



Since you ask me for the details of its characteristics and qualities, and 

 especially the way of illumination, not described by any pen before, by 

 way of an analysis, and since I have always complied with your wishes, I 

 believe I should start this obscure thing with a discussion of light. 



Then follows a rather obscure discussion of solar light or ethereal 

 fire, earthly fire, color, the noctiluca [glowworm] and eyes of cats. 

 Montalbani continued: ^ 



But I am convinced that the light of our stone that has been processed 

 has a different origin besides color, which it has in common with other 

 things that are mixed. In a definite, though hard to recognize measure- 

 on account of the arrangement of its parts— the light of the sun or fire 

 directly or reflected . . . ignites certain parts of this stone, be it calcined 

 or left intact. . . . These ignited parts are separated from the others by 

 calcination and ready to take up light or some inflammation and become 

 luminous. But we see this splendor, which shines in the dark, being 

 extinguished by what surrounds it, sometimes sooner, sometimes later, 

 depending on whether more or fewer of the dissoluble particles in the 

 whole of the mixed body have been ignited. ... As to the composition 

 of the stone, I am inclined to consider it, if not totally, at least pre- 

 dominantly arsenic with some admixture of sulphur and chalk. For, 

 exposed to great heat this stone, the pigment of gold, at once has a foul 

 smell, from a pale leaden color it turns yellowish, reddish, whitish, finally 

 blackish, while formerly it resembled the appearance of a crude simple 

 silex or a mostly roundish gypsum. Taken internally it causes very bad 

 vomiting; externally applied it has a depilating effect. 



Montalbani then described the external appearance of the stone, 

 which existed in three varieties, and closed his letter as follows: ^ 



I send you various fragments of the genuine stone, which show a dark 

 red vivid light, [or] slightly indicated, the blue smooth flame of sulphur, 

 [or] something like rare fiery embers. . . . 



He then continued: 



I leave you the road free for deeper speculation, since you know how to 

 sustain any light in a purer state by virtue of your sharp intellect. Be 

 sure that I was more concerned with your wishes than my own reputa- 

 tion and also that I live more for my friends than for myself. May God 

 give you all you deserve. Farewell. 



Apart from the flowery compliments with which these correspon- 

 dents greeted each other, the letter of Montalbani is of special in- 

 terest as indicating the different colors of luminescence which were 

 obtained and the first suggestion that the light was a kind of burning. 



