502 BAROX vox WREDE OX THE ABSORPTIOX OF LICIIT. 



lation were comparpd with the distance between two consecutive mi- 

 nima instead of with the differences betAvet n the representing lengths 

 of undulation, which would presuppose that the refrangibility of a colour 

 M'ould be proportional to its length of undulation, this can be consi- 

 dered as proving nothing more than that the reasoning and the expe- 

 riment coincide in showing that the absorptions in the green colour lie 

 closer to one another than in the red. 



I must finally remark that, although I have considered the retarda- 

 tions only as arising from reflection between the particles, I also easily 

 conceive the possibility that this idea may be incorrect, and that all the 

 retardations may arise from causes as yet quite unknown to us. But 1 

 think I have shown by what I have stated that the phaanomena of ab- 

 sorption may be reduced to a simple mathematical principle ; and that 

 these phaenomena, as belonging jiroperly to the absorbing l)odies, point 

 to certain determined magnitudes, which can be given in an absolute 

 measure, and tlie closer examination of whioli, wliatsocver their cause 

 may be, must always be highly inteiTsting. 



