410 



COLOURS. 



We shall now give a brief account of the different 

 pigments or colours, which are used either in water 

 or oil, for the purposes of drawing or painting. 



Red Colours. 



Lakes. This term is used to denote a species of 

 colours formed by the combination of alumine, or 

 the oxyd of tin, with the colouring matters of 

 vegetables. 



The lakes chiefly used are red colours, and these 

 are of different qualities, according to the basis and 

 colouring matter employed. 



The principal lakes are carminey Florence-lake ^ 

 and madder-lake. 



Carmine is a very ricli bright crimson colour, 

 and stands well in water. For the preparation of 

 carmine, four ounces of finely-pulverized cochineal 

 are to be poured into four or six quarts of rain, or 

 distilled water, that has been previously boiled in a 

 jjervter kettle, and boiled with it for the space of 

 six minutes longer (some advise to add, during the 

 boiling, two drachms of pulverized crystals of 

 tartar). Eight scruples of Roman alum, in pov/der, 

 are to be then added, and the whole kept upon the 

 fire one minute longer. As soon as the gross 

 powder has subsided, and the decoction has become 

 clear, it is to be carefully decanted into large 

 cylindrical glasses, covered over, and kept undis- 

 turbod, till a fine powder is observed to have settled 

 at the bottom. The liquor is then to be poured 

 oft from this powder, which is to be gradually dried. 

 From the liquor, which is still much coloured, the 

 rest of the colouring matter may be separated by 



