492 ON THE ABSORPTION OF LIGHT 



to suppose the luminiferous molecules of gross bodies 

 to be identical with their ultimate chemical atoms. I 

 should rather incline to consider them as minute groups, 

 each composed of innumerable such atoms ; and it 

 may be that in what are called uncrystallized media, 

 the axes or lines of symmetry of these groups may have 

 no particular direction, or rather all possible directions, 

 or the groups themselves may be unsymmetrical. Such 

 a disposition of things would correspond with a uniform 

 law of absorption, independent of the direction of the 

 transmitted ray; while in crystallized media a uniformity 

 of constitution and position of these elementary groups, 

 or rather of the cells or other combinations which they 

 may be regarded as forming with the interfused aether, 

 may be readily supposed to draw with it differences in 

 their mode of vibration, and even different disposals of 

 their nodal lines and surfaces, according to the different 

 directions in which undulations may traverse them : and 

 which may not impossibly be found to render an account 

 of the change of tint of such media according to the 

 direction of the rays in their interior, as well as of the 

 different tints and intensities of their oppositely polar- 

 ized pencils ; of which latter class of ph^enomena, 

 however, I shall immediately have occasion to speak 

 further. 



(i8.) But as my present object is merely to throw out, 

 as a subject for examination, a hint of a possible explana- 

 tion of the phgenomena of absoi:[)tion, on the undulatory 

 theory, I shall not now pursue its application into any 

 detail, nor attempt the further development of particular 



