OP COMMON HATTER. 149 



would be arrested by the air, as they are found 

 to be, by the opacity of a cloud, or of a fog; 

 and if the air were colored, the light in its 

 passage through it, would be constantly tinged 

 and dyed by the color of the medium. That 

 this would be the case, is clearjy demonstrated, 

 by the effect which is produced on the rays of 

 light when they pass through the medium of 

 glasses stained with different colors ; the color 

 of the glass is always found to stain the rays of 

 light, and convey to the eye its particular co- 

 lor : through a green glass, a body looks 

 green ; through a red glass, it looks red ; and 

 the influence which a jaundiced eye possesses, 

 of rendering bodies seen by it to appear yellow, 

 has been often noticed.* 



The different states of the medium which I 

 have described, may be considered as unna- 

 tural and morbid ; arising from the union and 

 diffusion of different bodies, which have insi- 

 nuated themselves into it. If the colored state 

 of the medium through which objects are be- 

 held, produces these unnatural consequences, 



* Although I have known this sensation occasionally to 

 happen, it is not generally the case ; when it does happen, it 

 is only in those extreme cases of jaundice, when a large quan- 

 tity of bile has been absorbed, and conveyed into the blood ; 

 and incorporated to a considerable degree, with the cornea 

 and the humors of the eye. 



