Egyp′tian Az′ure. Alexan′drian Frit, Azure of the Ancients. A mixture of carbonate of soda, 1 lb.; calcined flints, 11⁄2 lb.; copper filings, 1⁄4 lb. (all in fine powder); fused together in a crucible for 2 or 3 hours, and when cold, reduced to an impalpable powder. A beautiful and unchangeable sky-blue colour. Used in both oil and fresco painting; and as a substitute for smalts, of which, indeed, it is a variety.
In′digo (which see).
Blue, I′ron. Fer′ric blue. Ordinary phosphate of iron prepared by precipitating a solution of protosulphate of iron with another of phosphate of soda, the resulting powder being washed, and dried at a gentle heat. A lively sky-blue colour, but without much depth or body.
Blue, Lake. See Lakes and Indigo, Sulphate of.
Blue, Molybde′num. From sulphuret of molybdenum, dissolved in nitric acid, and some tin filings and a little muriatic acid added. After digestion for some time the clear liquid is poured off, and evaporated to dryness. The resulting powder is then mixed with moist hydrate of alumina (as in making cobalt blue), heated to a very dull red, and when it has
again become cold, reduced to powder. Used both as a paint and an enamel-colour.
Blue, Moun′tain. Native carbonate of copper, mixed with more or less earthy matter, reduced to fine powder. That of the shops is often factitious.
Blue, Par′is. Prussian blue.
Blue, Pow′der. Smalts.
Blue, Prus′′sian (which see).