[ 149 ] 



— it fliould be thus prepared before the grind- 

 ing. 



There are two ufeful colours I have not men- 

 tioned, white and black, which fome count no 

 no colours at all. I think they may be termed 

 the two extremes of colouring, fmce the one is 

 the ftrongeft light we can lay on, and the other 

 the deepeft fhade. Thefe are feldom ufed pure, 

 but are mixed with other colours. The white 

 (where colours are laid on in a body) mixed, in 

 different proportions, with any other colour, 

 makes all the variety of fhades that the two 

 colours fo mixed are capable of producing. 

 White may be compounded with any fimple or 

 compound colour, to produce different fhades 

 thereof. Black is often mixed (a little of it) in 

 the fhades, where the objeâ: is of a beautiful and 

 ^nd primary colour, as red, blue, or yellow ; for 

 thefe colours, lhadowed with fine dark colours 

 of their own fpecies, would be too glaring, and 

 quite unnatural -, fo that it is neceffary to allay 

 them with black, or fome dull colour ; for if 

 you obferve nature itfelf, for example, a fine 

 red or blue garment, it will appear exceeding 



fine 



