ABSORPTION OF LIGHT, ETC. 53 



as in this aniline glass between reflection and absorption, 

 but whereas in the aniline colours it is commonly the 

 phenomena due to absorption, and the selection of one kind 

 of light over another in the act of transmission, which 

 meet your eye, in the case of the metals gold and copper 

 it is a selection which takes place in the act of reflection 

 which ordinarily presents itself to observation, and the true 

 colour by transmission is only seen under very exceptional 

 circumstances. 



