COLOURS. 4^17 



large quantities, chiefly in France near Montpel- 

 lier, by stratifying copper-plates with the husks of 

 grapes yet under vinous fermentation, which soon 

 grow acid, and corrode the copper. After the 

 plates have stood in this situation for a sufficient 

 time, they are moistened with water, and exposed 

 in heaps to the air. The verdigris is scraped off 

 from their surface as it forms. 



Verdigris is of a bluish-green colour, but has no 

 body, and does not stand. It is only used for 

 very coarse purposes. It answers best when used 

 in varnishes. 



Distilled verdigris^ sometimes called crystals of 

 verdigris, is prepared from common verdigris, by 

 dissolving it in vinegar. It is of a very bright 

 green, and is used chiefly for varnishes, and in co- 

 louring maps, &c. 



Brown Colours. 



Bistre is the finer part extracted from the soot 

 of burnt wood. It is much used for sketches in 

 water-colours, being a transparent warm colour. 



Cologne earth. This is a mineral substance of 

 a dark blackish brown colour. It is a very useful 

 colour ; though what is generally sold in the shops 

 for Cologne earth is an artificial mixture of several 

 colours. 



Raw timbre is a native ochreous earth, of a light 

 brown. It stands well. 



Burnt umhre. This is only the last mentioned , 

 colour, calcined in the fire. It then acquires a rich 

 deep brown, and is of great use, being a fine 

 colour, and standing perfectly well. 



Asphaltum. This colour is used in oil, and is of 

 a very rich deep brown. It is a transparent or 

 glazing colour. It will not work in water, but 



VOL. II. E E 



