462 Count Rumford’s Inquiry concerning the 
The following experiments, which were first suggested by an 
accident, were made with a view to investigate still farther the 
causes of those effects which have been attributed to the sup- 
posed chemical properties of light. 
Having accidentally put away two small phials, each con- 
taining 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 having been transferred to the ether, and 
the solution being left colourless ; in one of the phials, which 
happened to stand in a window in which there was occasionally 
a strong light, (though the direct rays of the sun never fell on 
it,) I found, in about three weeks, that the oxide was almost 
entirely reduced ; the revived gold appearing in all its metallic 
splendour, in the form of a thin pellicle, swimming on the sur- 
face 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 conceived, 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 experiment, with a view to the farther investigation 
of that matter. 
Experiment No. 13. Into a small pear-like phial, of very fine 
transparent glass, I put equal quantities of an aqueous solution 
of the muriatic oxide of gold and sulphuric ether ; and the phial. 
