This section is from the book "Chromatography; Or, A Treatise On Colours And Pigments, And Of Their Powers In Painting", by George Field. Also available from Amazon: Chromatography, or A Treatise on Colours and Pigments, and of Their Powers in Painting.
Terra Di Sienna, Or Raw Sienna Earth , etc. is also a ferruginous native pigment, and appears to be an iron ore, which may be considered as a crude natural yellow lake, firm in substance, of a glossy fracture, and very absorbent. It is in many respects a valuable pigment, - of rather an impure yellow colour, but has more body and transparency than the ochres; and being little liable to change by the action of either light, time, or impure air, it may be safely used according to its powers, either in oil or water, and in all the modes of practice. By burning it becomes deeper, orange, and more transparent and drying. See Burnt Sienna Earth.
Iron Yellow, Jaune De Fer, Or Jaime De Mars, etc, is a bright iron ochre, prepared artificially, of the nature of Sienna earth. In its general qualities it resembles the ochres, with the same eligibilities and exceptions, but is more transparent. The colours of Iron exist in endless variety in nature, and are capable of the same variation by art, from sienna yellow, through orange and red, to purple, brown, and black, among which are useful and valuable distinctions, which are brighter and purer than native ochres. They were formerly introduced by the author, and have been lately received under the names of orange de mars, rouge de mars, brun de mars, names which have the merit at least of not misleading the judgment. When carefully prepared, these pigments dry well in proportion to their depth, and have the general habits of sienna earths and ochres.