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thofe who fer out in painting or colouring, to 

 be furnilhed with all of them, which may fave 

 fome trouble in compounding. 



I fliall give here a few hints on the preparing 

 of colours, though this fubjefl has been largely- 

 handled already. — Common reafon will teach 

 one to reduce all hard fubftances by grinding 

 them well on a ftone, and after grinding them, 

 to levigate them finely in water, by pouring 

 them feveral times out of one vefTel into another, 

 after ftirring them, and letting the gritty and 

 groffer parts fettle : this not only takes out all 

 the gritty and grofs particles, but frees many 

 earthy and mineral colours from corrofive faits, 

 which would have a bad effed, by making a 

 work fpotty, or changing the colours, as well as 

 attracting moifture, which in time is apt to rot 

 the canvas or paper on which they are laid. 



There are fome few colours which are only 

 gums ; thefe are gamboge and fap-green : tliey 

 hold themfelves on the paper without any addi- 

 tional gum ; but all the mineral, or earthy co- 

 lours, muft be mixed with a due proportion of 

 L 2 gum- 



