308 History of Luminescence 



pierre potier 



The first detailed description of the method of preparing the 

 stone was published by Pierre Potier or Poterius (died 1640) , physi- 

 cian to the kings of France, in a section of his Pharmacopoea Spa- 

 girica (1625) , dealing with inorganic remedies based on the teach- 

 ings of Paracelsus. The account ^ first appeared at Bologna in 1622 

 and as Potier lived in that city for some time, he was able to give a 

 reliable version of the discovery. He began with acclamation of the 

 marvels discovered in his time: ^ 



Daily there emerge new things in nature, in which its great miracles are 

 appearing. O you idle haters of truth who are ashamed of learning 

 more. Wrongly we believe that everything was known to the ancients. 

 How many plants, how many fossils not seen by our ancestors have 

 come to light! Among other phenomena unknown to them there appears 

 to us something special in the class of stones which is quite new and 

 unheard of. . . . It is wonderful how a dark body receives its light from 

 the sun or moon and reflects it in the dark. Which makes us wonder 

 whether light is a body and what kind of a body; or a substance or an 

 accident, and other questions on light which perhaps it is not difficult 

 to elucidate. 



There then follows a minute description of the appearance and 

 properties of the stone itself and the parts of Monte Paterno where 

 it is found, with the receipt for preparation: 



According to the light-bearing quality sought for it is calcined in two 

 ways: the first is to reduce the stone to very fine meal, then to calcine 

 it in a crucible with a very strong fire. The second to reduce it to meal 

 and, in the place of thalemm (?) , work it into cakes either with plain 

 water or the white of an egg. After they have dried out they are put in 

 layers with coal in a blast furnace and, after a very hot fire has been 

 made, they are calcined four or five hours. When the oven has cooled 

 off the cakes are taken out. If not cooked sufficiently the performance is 

 repeated as before. Sometimes this is done three times. The best calci- 

 nation is the one made from choice stones, shining, pure, and dia- 

 phanous. . . . From this powder various animals are formed in little 

 boxes (pyxidiculum) which shine wonderfully in the dark. The lixivium 

 is prepared in the same way and once it is dry it produces a sulphurous, 

 fetid, sharp, and biting salt. 



Potier did not attempt an explanation of the light. On the con- 

 trary he said, " Those who like to settle disputes over minute points 

 may, concerning the uncommon things told about its light, speculate 



' Translated into German by L. Vanino, Die Kilnstlichen Leuchtsteine, 10-14, 1906, 

 and Die Leuchtfarben, 2-5, 1935. 



* Translated from the Latin by Mrs. Anneraarie Holborn. 



