?02 Researches in regard to the Ma?iiier 



its close connection with the colours of bodies, and to form 

 from it a system which, as a monument of human inge- 

 miity, is worthy of admiration. 



Some of the supports of this system of colours, which at 

 present is made the ground of the explanation given of the 

 phaenomcna of colours, have been shaken by Eulcr's hypo- 

 thesis ; but it can by no means be entirely overtunied. 



Newton's experiments on the refraction of the rays of 

 light, have undoubtedly proved that light must he considered 

 as the first and only cause of all colours, and be made the 

 principle on which they are explained. 



But when we found on it the hypothesis, that white light 

 is a mixture of the seven simple coloured rays, which can 

 no longer be decomposed, and when this hypothesis is made 

 the foundation of another, to show how the natural bodies 

 exhibit their colours according as they reflect this or that 

 ray of light and absorb the rest, — this to me appears to be 

 ■merely an auxiliary hypothesis, capable of explaining the 

 consequence in part, but by no means entirely. 



Had Newton, the celebrated author of this system, been 

 as good a chemist as he was a geometrician and philosopher; 

 and had the knowledge of chemistry been as widely extended 

 in his time as it is at present; that great man, as modest as 

 he was free from prejudice, would in the prosecution of his 

 discoveries have proceeded to the first causes ; and these re- 

 searches would have exhibited to so philosophical and accu- 

 rate an experimenter the object of his inquiries in a diffe- 

 rent point of view. 



This, however, was not the case. Newton, and most of 

 his followers who employed themselves with researches on 

 this subject, examined rather the refrangibility and reflexi- 

 bility of liglit than its intimate nature ; and therefore it was 

 unavoidable that phsenooiena should either escape or be con- 

 cealed from them, which are every moment produced by 

 the action of light, and which in its eflccts act a distin- 

 guished part as the means of producing colours. 



Some new experiments which I niade on light, and a re- 

 petition of those of others, have exhibited to me phaeno- 

 mcna which seem to merit attention, as they may serve to 

 enable us to form some opinion in regard to the object in 

 question. 



That I may pursue these experiments in systematic order, 

 I shall here mention the ideas which gave birth to tnem : 

 they were as follows : 



1st, Is the white colourless light a simple and not a com- 

 pound substance ? 



2d, Is 



