414 COLOURS. 



Verditer is a blue pigment, obtained by adding 

 chalk or whitening to the solution of copper in 

 aqua fortis. The best sort is prepared by the 

 refiners, who employ for this purpose the solution 

 of copper, which they obtain in the process of 

 parting, by precipitating silver from aqua fortis by 

 plates of copper. Common verditer is made from 

 the sulphate of copper, or blue, by the manufac- 

 turers in Sheffield and Birmingham, Verditer is 

 only used for very coarse purposes, chiefly by the 

 paper-stainers. It has been sometimes called 

 SANDERS blue, from ignorance of the meaning of 

 the term cendres blues, or blue ashes, which the 

 French call it. 



Indigo. This colour is extracted from a plant 

 called Anil, that grows in the East and West 

 Indies. It is not so bright as Prussian-blue, but it 

 is cooler, and has the advantage of being very 

 durable. When dissolved by the sulphuric acid, 

 it forms SCOTT'S liquid blue, so much used for 

 colouring silk stockings, &c. 



Smalt. This is glass coloured with cobalt, and 

 ground to a fine powder. Its coarseness prevents 

 its being used much for painting in oil or water. 

 It is employed sometimes by sterwing it upon a 

 ground of oil-paint. It is also used in enamel- 

 painting. It stands well. 



Blue Bice. This is only smalt more finely levi- 

 gated. 



Yellow Colours. 



Indian yellow. This is the brightest of all yel- 

 lows for water-colours, and is perfectly durable. 

 It is said to be procured from the urine of the 



