268 Afr. De^aval on the Cattje of the 



they feeiTi rather to have yielded to the authority 

 of Sir Ifaac Newton, and other theorifts, than 

 to have appealed to the operations of their own 

 art, from which the real caufe and oiigin of colours 

 is obvioudy deducible. 



The Art of Dying confids, principally, in cover- 

 ing white fubftances, from which light is ftrongly 

 refletftedjwithTranfparentColoured Media, which, 

 accordingly to their feveral colours, tranfmit, 

 more or Jefs copiouny, the feveral rays refleded 

 from the white fubftances. 



The Tranfparent Coloured Media themfelves 

 refle6V no light : and it is evident that, if they 

 yielded their colours by reflcfling, inftead of tranf- 

 mirting, the rays, the whitenefs, or colour of the 

 ground on which they are applied, would not 

 anywife alter, or affed, the colours which they 

 exhibit. 



Such an erroneous conception of the principles 

 of the art, cannot fail greatly to obftrudt its pro- 

 grefs, and improvement. All colouring matter 

 is black, when viewed by incident light, and all 

 fubftances incline to blacknefs, in proportion as 

 they are copioufly ftored with tinging particles. 



The A rtiil therefore, who confines his inquiries 

 ' to fubftances which refleft the light, cannot be 

 fuccefsful in his endeavours to difcover new dying 

 materials: and, if he is led, by experience, to ex- 

 tend his rcfearches to other fubftances, his prac- 

 tice contradiuts his principles \ by which his views 



are 



