Terre verte

Lead Chromate.—This is determined exactly as described for lead chromate in chrome yellows (g.v., paragraph 2). 

Mixed chrome greens usually contain considerable quantities (up to 80-90%) of inert substances in the commoner types the content of lead chromate varies from 3 to 10% and that of Prussian blue from 5 to 20%. 

Terre verte or Veronese earth is a magnesium clay coloured by ferrous silicate. It is very rich in silica and poor in alumina and usually contains, besides magnesia, also small quantities of alkali, and sometimes lime and carbonic acid. 

It is often improved with organic dyes (generally malachite green or one of its allies) and sometimes with copper green. It may, indeed, be replaced by inert matter coloured with artificial organic dyes. 

The examination of terre verte is commonly limited to technical tests of the covering power and of the fastness to atmospheric agents and to lime, and to tests for the presence of artificial organic dyes (usually by treatment with alcohol). The presence of copper colours may be detected by treatment with ammonia. 

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Green earth Naturally occurring earth pigment, which is primarily an iron silicate. Used to make lime green. Syn terre verte. 

Terre verte n. Essentially an iron sihcate. It is used as a base for lakes. Syn green earth. 

Specific use of the term Verona brown appears to have been a nineteenth century introduction. Merrifield (1849), for example, states in a discussion of burnt green earth that modem writers do not mention this colour, but the use of it has been revived by an eminent English artist, under the name of Verona Brown . Linton (1852) states that When calcined, [terre verte] forms another beautiful pigment called Verona Brown. However, Salter (1869) calls it a native ferraginous earth without indicating other processing. Toch (1916) says that Verona brown was a fancy name for a mixture of burnt umber and burnt or raw sienna. By the time Heaton was writing in 1928 he considered the term to be obsolete or only rarely used. 

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