COLOURS* 417 



large quantities, chiefly in France near Moritpel- 

 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 umbre is a native ochreous earth, of a light 

 brown. It stands well. 



Burnt umbre. 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 



