PHOSPHORESCENCE. 45 



Freyburg, observed the branches of the trees glow- 

 ing with a bluish light. 



Francois Arago has collected many instances of 

 luminous rain, among which are the following : 



On the 3rd of June, 1731, Hallai, an ecclesiastic 

 of Lessay, near Constance, states that he saw, in 

 the evening, during a thunderstorm, rain which 

 fell like drops of red-hot liquid metal. 



In 1761, Bergman, the celebrated Swedish 

 chemist, wrote to the Royal Society of London 

 that he had observed on two occasions, towards 

 evening, and when no thunder was heard, rain 

 which sparkled as it touched the ground, making 

 the latter appear as if covered with waves of 

 fire. 



On the 3rd of May, 1 768, near Arnay-le-Duc, 

 M. Pasumot was overtaken on an open plain by a 

 violent storm. The rain-water collected abun- 

 dantly on the border of his hat; and when he 

 stooped his head to let it flow off, he observed 

 that, in its fall, encountering that which fell from 

 the clouds, at about twenty inches from the ground, 

 sparks were emitted between the two portions of 

 liquid. 



On the 28th of October, 1772, on his way 

 from Brignai to Lyons, the Abbe Bertholon was 

 caught in a storm at five o'clock in the morning. 

 Bain and hail fell heavily. The drops of rain and 

 the hailstones which struck against the metallic 



