332 COLORIFICATION IN GENERAL. 



the diversity, of color, principally depends on 

 the quality of the base with which colorless 

 light has combined ; that it is owing to this 

 combination which has taken place between 

 both, that a new substance (a tertium quid) is 

 formed, which is colored since it is visible ; 

 and, which is visible, because it is combined ; 

 the properties of which are very different in 

 their combined, from what they were in their 

 simple elementary state. The matter of light 

 from being colorless, becomes colored, from 

 being invisible, it becomes sensible, from be- 

 ing transparent Only, it participates, in an emi- 

 nent degree, in the opacity and quality of the 

 base, with which it has united ; the result of 

 which is the production of color. So long., 

 therefore, as the eye becomes illuminated by 

 any object whatever, that object must be con- 

 sidered to be colored. Illumination constitut- 

 ing the genus, of which color is the species. In 

 order, therefore, that vision should exist, it is 

 necessary that the rays of color which are trans- 

 mitted or reflected from different bodies, should 

 unite, in the eye, in the same order as they 

 exist in the substances from whence they have 

 issued, or whence they have been reflected. 



The change of color, which different bodies 

 undergo, by exposure to the solar rays, and 

 more especially the facility which we possess, 

 of collecting these colored rays by means of 



