244 T. Gaffield on the action of Sunlight on Glass. 
Arr. XXVIII—The Action of Sunlight on Glass; by THOMAS 
GAFFIELD, 
THE great attention now given to all the phenomena connected 
with light and heat may awaken some interest in the experi 
ments in which I have been engaged for the past four years on 
the subject named at the head of this article. Perhaps I cannot 
‘ter commence my essay, than by quoting from the “ Proceed- 
to intense sunlight. One case* is cited of a change to a gold 
color; and one experiment recorded by Dr. Faraday,t some 
sagen proving that a light purple changed toa darker 
eight month’s exposure. 
of diffe &F experiments are on record showing the action of gla 
heat : She colors as media in the transmission of light and 
‘Tact Lone With the above exception, showing the 
“An tomes or eae dow-glass 
: “rrence of some twenty years in the window-g 
—- Paes only presented a ed 7 lated cases of supposed 
see O color from this cause, which were attributed to some 
obvious defect in an article of inferior manufacture; but, witbi2 
+ poumal of Society of Arts for Feb. " 
t Dr. Faraday’s Chemical Researches, sien 1859, p. 142. 
