Cologne earth

The most common of these pigments are certain earths, such as Sienna or Italian earth—which is a brown ochre—umber, Cologne earth or Cassel brown blacks with a carbon basis graphite, consisting of more or less impure crystalline carbon. 

This is a species of earthy peat, ground and suitably punnett tt- consists principally of humous and carbonaceous matter. It forms a light, brown powder, which, when heated in the air, burns with moderate ease, giving no flame and emitting a bituminous odour. It may be mixed with ochre, umber and ferric oxide, such mixtures (prepared Cologne earth) being sold under various names. 

Its examination includes, besides the usual technical tests, the following chemical tests, which indicate mainly if the Cologne earth is pure or mixed with any of the substances indicated above. 

Cologne earth, if pure, does not leave more than 10% of ash, which is whitish or faint pink, and does not contain more than traces of iron if the ash exceeds this amount and is red, the product is mixed with umber, ochTe or ferric oxide. 

Further, pure Cologne earth gives up not more than a trace of iron to hydrochloric acid, and when treated with caustic potash it should not leave an abundant heavy residue. 

Van Dyke brown. (Cassel brown Cologne brown Cologne earth ulmin brown). A naturally occurring pigment. 

Cologne earth Cologne umber. See Manganese oxide (ic)... 

Colloid Protein. See Collagen Colloxylin. See Nitrocellulose Cologel. See Methylcellulose Cologne earth Cologne umber. See Manganese oxide (ic)... 

Cologne earth, cologne brown n. A pigment, sometimes referred to erroneously as Vandyke brown, made from roasted... 

Chalon s brown is decribed by Salter (1869) who gives no direct information about its composition. However, he groups it between Cassel and Cologne earths, so that it was probably a humic earth (qq.v.). 

Humic earth Cassel earth-, Cologne earth Salter (1869) 344... 

Cologne earth is generally described as a form of humic earth (. v.) and compared or equated to Vandyke brown. Salter states that it was also incorrectly called CuUen s earth (Salter, 1869). It is also known as German innber and Cologne u. (Tingry, 1804). 

Earth pigments group Hydrocarbons group Lignite Ochre Sienna Cassel earth Cologne earth Vandyke brown Feller Johnston-Feller (1997)... 

Lignite-based pigments are hsted under the terms Vandyke brown and its synonyms Cassel earth qq.v.) and Cologne earth (Feller and Johnson-Feller, 1997). Nocera earth is also rich in humic earths, and siennas (. v.) are described by some authors as having traces of oiganic or peaty material (Church, 1901). 

Humic earth Lignite Cappagh brown Cassel earth Cologne earth Preto de Frondes Terra di colonia... 

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