DECOMPOSITION OF LIGHT. , %$ 



the effects of absorption, which ultimately leaves only red, 

 green, or violet rays; with the simple and natural explana- 

 tion of the principal appearances of the spectrum, by 

 means of three kinds of rays; with the happy manner in 

 •which these three kinds are applicable to the properties of 

 the dial of colours, and remove its complication; and I 

 think the whole will support my proposition. If it do not 

 Jience appear to the natural philosopher as a fact established 

 beyond all question, at least he cannot refuse to consider it 

 as already grounded on strong probabilities, and sufficiently 

 interesting to merit a thorough investigation, which my 

 occupations have prevented me from pursuing any farther. 



Recapitulation. 

 Thus our system of colours appears to. me reduced to Red and grceu 



these few data : three sorts of luminous ravs, of a parti- J uce yel ~ , 



• ' ' r ■ i low ; green and 



cular and unknown nature ; red, green, and violet. Cora- violet, blue. 

 T)ined by twos, the red and green produce yellow ; the intermediate 

 green and violet, blue; the violet and red, purple: the different pre- 

 three together produce white; and lastly, the intermediate P ortions - 

 shades are according to the proportional quantities of their 

 elements. 



Bodies exercise a general action on all the rays of light. Light analysed 

 aud a particular one relative to their peculiar nature. If b y re >racuon. 

 the 'White pencil fall obliquely on the surface of a trans- 

 parent body, the rays, as they penetrate it, deviate from 

 their original direction, some more,' others less, according 

 to their nature. Here we have a true analysis of white 

 light, in which its three simple elements may be found 

 separate, as well as combined, in different proportions. 

 It is thus that refraction exhibits a series of tints, which 

 differ, in different bodies, both with respect to their general 

 deflection, measured by its mean quantity, in the relative 

 dispersion of the rays, and in the particular position of 

 each colour. 



If the affinity of the body for the rays of light, be such Bodiescoloured 

 as to absorb some into its own substance, it will be coloured ; from absorbing 

 aHd will exert a preferable or stronger action on certain 

 sorts of rays. In a small mass, the body will fir^t absorb 

 these rays, to wjiich it has a preferable affinity ; and, if its 



action 



