Chemical Properties attributed to Light. 87 



about \\ inch in diameter at its bulb, was very thin, 

 and made of very fine colourless glass ; the aqueous 

 solution was also perfectly transparent and colourless ; 

 and, when the contents of the phial were illuminated by 

 the direct rays of a bright sun, the contrast of the 

 white colour of these little metallic spangles with the 

 black charcoal to which they were fixed, and their 

 extreme brilliancy afforded a very beautiful and inter- 

 esting sight. 



As the air had been previously expelled from the 

 charcoal by boiling it in distilled water, it was specifi- 

 cally heavier than the aqueous solution of the metallic 

 oxide, and consequently remained at the bottom of the 

 bottle. 



Experiment No. 12. A phial as nearly as possible 

 like that used in the last experiment, and containing 

 the same quantity of diluted aqueous solution of nitrate 

 of silver and also of charcoal, was enclosed in a cylin- 

 drical tin box, and exposed one hour to the heat of 

 boiling water, in an apparatus used for boiling vegeta- 

 bles in steam for the table. 



The result of this experiment was uncommonly 

 striking. The surface of the charcoal was covered 

 with a most beautiful metallic vegetation; small fila- 

 ments of revived silver, resembling fine flatted silver 

 wire, pushing out from its surface in all directions ! 

 . Some of these metallic filaments were above one 

 tenth of an inch in length. On agitating the contents 

 of the phial, they were easily detached from the surface 

 of the charcoal, to which they seemed to adhere but 

 very slightly. 



These experiments were repeated several times, and 

 always with precisely the same results. 



