Mr. T. Gaffield on the Action of Sunlight on Glass. 519 

 Table of Glasses easily changed. 



Kinds of glass. 



Original colour before exposure. 



5 of French white plate. 



2 of German „ 

 1 of English „ 

 5 of English plate. 



1 of Belgian rough plate. 



3 of French white sheet. 



1 of Belgian „ 



4 of English „ 



2 of American „ 



24 



White, with light bluish-green tinge. 



» » » 



»» >> >> 

 Yellowish green. 

 White, with slight green tinge. 

 White, with light bluish-green tinge. 

 White, with light yellowish-green tinge. 

 / One light yellowish-green, and three 

 \ light bluish-green tinge. 

 White, with light blue-green tinge. 



The time at which change of colour 

 was first observed. 



Colour after exposure. 



Days. 



Weeks. 



Months. 



1 



2 



4 



1 



2 



3 



1 



2 



3 



1 

 1 



1 



3 

 1 



"i 



4 

 1 



i' 



i 





i 

 T 



i 



... 





I 



•• 





... 



Yellow or yellowish green. 



ff r» » 



Deeper yellow tinge. 



Yellowish-green tinge. 

 » >> >» 

 » >» >» 



» >> >> 



8 



5 



6 



i 



3 





1 









Table of Glasses not changed in three months. 



Kinds of glass. 



kind of German crystal plate. 

 German plate. 

 English rough plate. 

 English crown. 

 American „ 

 American sheet. 

 English ,, 

 Belgian „ 

 French „ 



9 



Original colour of glass. 



Light green. 



Dark blue. 



Dark green. 



Light green. 



Bluish green. 



Dark bluish green. 



Dark green. 



Yellowish or brownish green. 



