4 59 
chemical Properties attributed to Light, 
Experiment No. 10. A cylindrical glass tube, of an inch 
in diameter, and 10 inches long, closed hermetically at its lower 
end, and containing a quantity of a diluted aqueous solution of 
the oxide of gold, mixed with charcoal in broken pieces, about 
the size of large peas, was put into a fit cylindrical tin case, 
. which was'nicely closed with a fit cover ; and the glass tube, 
with its contents, so shut up in the dark, was exposed two 
hours, in the temperature of 210° of Fahrenheit's scale. 
On taking the glass tube out of its tin case, I found the solu- 
tion perfectly colourless , and the revived gold adhering to the 
surface of the charcoal. 
On repeating the experiment, and using the solution nearly 
saturated with the oxide, the result was precisely the same ; 
the solution being found perfectly colourless, and the revived 
gold adhering to the surface of the charcoal. 
I own fairly, that the results of these experiments were quite 
contrary to my expectations, and that I am not able to recon- 
cile them with my hypothesis, respecting the causes of the re- 
duction of the oxide, in the foregoing experiments; but, what- 
ever may be the fate of this, or of any other hypothesis of 
mine, I hope and trust that I never shall be so weak as to feel 
pasn at the discovery of truth, however contrary it may be to 
my expectations ; and still less, to feel a secret wish to suppress 
experiments, merely because their results militate against my 
speculative opinions. 
It is proper 1 should observe, that the charcoal used in 
this last-mentioned experiment had been boiled two hours in 
distilled water, by which means its pores had been so com- 
pletely filled with that fluid, that the pieces of it that were 
3 N 2 
