Thenard’s blue

The salts have been used for centuries to produce brilliant and permanent blue colors in porcelain, glass, pottery, tiles, and enamels. It is the principal ingredient in Sevre s and Thenard s blue. A solution of the chloride is used as a sympathetic ink. Cobalt carefully used in the form of the chloride, sulfate, acetate, or nitrate has been found effective in correcting a certain mineral deficiency disease in animals. 

Cobalt Blue consists essentially of oxides of cobalt and aluminium with more or less zinc oxide. It is obtained by calcining a mixture of alum and cobalt sulphate, and is used by artists in painting porcelain. Save for this it has now no commercial value.13 Cobalt blue is also known as Cobalt Ultramarine, Thenard s Blue, and King s Blue. 

Detection.—Dry Tests.—Salts of cobalt are usually of a rose-red colour when hydrated, and yield a beautiful blue colour in the borax bead test provided they are not present in excessive amount, otherwise the bead becomes opaque and appears black. When heated on charcoal with reduction mixture in the blowpipe test, metallic cobalt separates out in the form of small magnetic beads. When strongly heated with alumina a blue colour is produced, known as Thenard s blue. 

II. Dry tests (blowpipe test) Aluminium compounds when heated with sodium carbonate upon charcoal in the blowpipe flame give a white infusible solid, which glows when hot. If the residue be moistened with one or two drops of cobalt nitrate solution and again heated, a blue infusible mass (Thenard s blue, or cobalt meta-aluminate) is obtained. It is important not to use excess cobalt nitrate solution since this yields black cobalt oxide Co304 upon ignition, which masks the colour of the Thenard s blue. 

Thenard A process for making white lead pigment (basic lead carbonate) by boiling litharge (lead monoxide) with lead acetate solution and passing carbon dioxide gas into the suspension. L.J. Thenard (1777 to 1857) was an eminent French chemist, more famous for his invention of Thenard s blue (cobalt aluminate). 

Cobalt aluminate spinel Cobalt blue Pigment blue 28 Thenard s blue Empirical AI2C0O,... 

TFE/HFP. See Fluorinated ethylene/propylene TGA 2. See Diethylene glycol diacrylate TGIC. SeeTriglycidyl isocyanurate TGM3. See PEG-3 dimethacrylate Thalo green No. 1. See Phthalocyanine green THAN. SeeTris (hydroxymethyl) aminomethane THBP. See Benzophenone-2 Thenard s blue. See Cobalt aluminum oxide Thermal acetylene black Thermal atomic black Thermal black. See Carbon black... 

Thenard s blue. See Cobalt aluminum oxide 2-Thenoic acid... 

Thenard s blue n. Another name for cobalt blue. 

Thomson says Wenzel never obtained the confidence of chemists, nor is his name ever quoted as an authority , and his book (I) fell almost dead-bom from the press — yet it was republished twice. I have also found Wenzel quite often quoted, but by later writers in error for Richter (see p. 676). Among his discoveries was the blue mass formed from alumina and cobalt oxide, usually called Thenard s blue (Thenard, 1805, see Vol. IV) but first noticed by Gahn. Wenzel also recognised that iron becomes passive in concentrated nitric acid. ... 

Thenard s Blue. A dark blue colour for use under-glaze in pottery decoration it consists of approx, four parts cobalt oxide to five parts alumina. 

Many cobalt pigments are used in oil paintings cobalt blue - a siHcate, Thenard s blue - an aluminate, cobalt violet - a phosphate. 

Bouvier (1827) mentions acetate of cobalt as a composition of Thenard s blue (. v.) reported to him by a chemist. However, this... 

Riederer thereafter discerns a general decrease in application, first in Italy and then in the Netherlands. Miihlethaler and Thissen regard the invention of Prussian blue, the discovery of synthetic ultramarine and of Thenard s blue (qq.v.) as the reason for the decline in usage of smalt (Muhlethaler and Thissen, 1993), although examples continue, such as specimens contained in the Hafkenscheid Collection (Pey, 1987). The pigment is currently available. 

Co(OAc)2 71-48-7 Bouvier (1827) 46 As reported composition of Thenard s blue (probably erroneous)... 

Wenzel is said to have described the blue mass formed with cobalt oxide and alumina, afterwards called Thenard s blue this had been noticed by Gahn (see Vol. Ill, p. 201). The process was described by Chaptal, who says he initiated the research by Thenard and Merime. Thenard investigated the oxides and salts of mercury, phosphates of soda and ammonia, nickel, compounds (alloys) of antimony and tin, oxides of iron and other metals, mordants, a supposed black phosphorus, and phosphorous acid (which he found contained 100 phosphorus +110 39 seep. 60). He obtained... 

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