88 An Inquiry concerning the 



When the oxide of gold was reduced In this way, 

 the revived metal appeared under the form of small 

 scales, adhering firmly to the surface of the charcoal, 

 as has already been observed. 



The following experiments, which were first sug- 

 gested by an accident, were made with a view to inves- 

 tigate still farther the causes of those effects which 

 have been attributed to the supposed chemical prop- 

 erties of light. 



Having accidentally put away two small phials, each 

 containing a quantity of aqueous solution of the oxide 

 of gold and sulphuric ether, in each of which the ether 

 had extracted the gold completely from the solution, as 

 was evident by the yellow colour of the solution hav- 

 ing been transferred to the ether, and the solution 

 being left colourless, — in one of the phials which hap- 

 pened to stand in a window, in which there was occa- 

 sionally a strong light (though the direct rays of the 

 sun never fell upon it), I found, in about three weeks, 

 the oxide of gold was almost entirely reduced ; the 

 revived gold, appearing in all its metallic splendour in 

 the form of a thin pellicle, swimming on the surface of 

 the aqueous liquor in the phial, and the colour of the 

 ether which reposed on it having become quite faint; 

 while no visible change had been produced in the 

 contents of the other phial, which had stood in a dark 

 corner of the room. 



As these appearances induced me to suspect, or 

 rather strengthened the suspicions I had before con- 

 ceived, that the separation of gold from ether under its 

 metallic form, when a solution of its oxide is mixed 

 with that fluid, is always effected by a reduction of the 

 oxide by means of light, I made the following experi- 



