T. Gaffield on the action of Sunlight on Glass. 251 
I subjoin an account of an experiment carried on for one year 
with nine different kinds of glasses. These represen ate, 
crown and cylinder glass, the manufactures of bot hentia 
and almost every shade and color of what are called colorless 
asses 
I name only the nationalities, and not the particular manu- 
factories of the glasses in any of my tables. 1 have this infor- 
mation recorded in my journal, and shall be happy to commu- 
ni¢ate it to any who may desire it. 
Memorandum of nine different kinds o glass exposed from Jan, 12, 1866, to Jan. 
1 
2, 1867. 
"Pee eg A 
Kind of glass. | Color before exposure. Color after exposure. | 
"screamed 
French white plate. Bluish white. Yellowish color. 
German crystal plate. Light green, Bluish tinge 
English plate, e : Yellowish green. 
English crown * < Light purplish color. 
Belgian sheet. Brownish yellow. a % 
7 English sheet. Dark green. Brownish green. 
| American crystal sheet. | Light bluish white. Purplish white. 
4 “ He Lighter bluish white. Light yellowish green. 
“ordinary “ Bluish green. No change. 
of the year, by the comparative depth of yellow or purple 
Color produced in the various specimens m: 
parative actinic power of the rays during each month and season. 
The results proved that the actinic effect increased from Jan- 
wary to J uly, and decreased after that month. The greatest 
“ect during any season was observed in the summer, the least 
i Winter, and that in spring and autumn was about alike, and 
Way between that of summer and winter. ; 
Crystal or lead glass, and a piece of optical glass having bint 
. . . rs. ? 3 
hay periments with artificial heat on glass in vari- 
OU ways, from ae to the heat of a cooking range oven 
