PHOSPHORESCENCE. 45 
Freyburg, observed the branches of the trees glow- 
ing with w bluish light. 
Francois Arago has collected many instances of 
luminous rain, among which are the followmg :— 
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, 1768, near Arnay-le-Duc, 
M. Pasumot was overtaken on an open plain by a 
violent storm. The ram-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 enitted between the two portions of 
liquid. 
On the 28th of October, 1772, on his way 
from Brignai to Lyons, the Abbé Bertholon was 
caught in a storm at five o’clock in the morning. 
Rain and hail fell heavily. The drops of rain and 
the hailstones which struck against the metallic 
