Copper Indigo

Cupric sulphide occurs in nature as covellite or indigo-copper, indigo-blue, hexagonal plates, density 4-59 to 4-64, and hardness 1-5 to 2.13 The dark-green, amorphous variety has the density 4-16,14 and is a good cbnductor of electricity.15 It is decomposed in vacuum at 400° C. into cuprous sulphide and sulphur.16 Its oxidation by air in ammoniaeal, neutral, and acidic suspensions is similar to that of cuprous sulphide... 

Indigoid soluble dyes, 7 373t Indigo vat dye, 9 181 Indirect-arc furnaces, 12 297—298 Indirect coal liquefaction, 6 858-867 Indirect cooler evaporators, 21 537 Indirect extrusion, copper, 7 693 Indirect food additives, 12 29, 34 categories of, 12 31 Indirect-gap semiconductors, 14 837 ... 

Having performed the preliminary practice as just described, rise from the chair in the Chamber of Indwelling. On the right side of the copper-sheathed door facing you is a clothes-stand on which hangs a cowled indigo robe. Beneath it are a pair of silver sandals. Rise and put on the robe, step into the silver sandals, and raise the hood of the robe. Open the door, step through it, and close it behind you. This door bears the enameled apas-tejas plate. 

Indium was discovered by Reich and Richter in 1863 in Germany during spectroscopic observations of local zinc ores. The new element was named indium after its characteristic indigo blue spectral lines. Although widely distributed in nature, its concentration is very low, estimated to be about 0.1 mg/kg in the earth s crust. It is found mostly in zinc sulfide ores and to a lesser extent in sulfide ores of iron and copper. The metal does not occur in free elemental form in nature. 

He published papers on the composition of coal, wood, charcoal, steel, pyrolusite, molybdenite, and spring waters, on the arts of purifying lead, hardening copper, and burning bricks, on the working of saltpeter and indigo, on resuscitation of patients with suspended animation, and on the porphyry industry at Elf dal, East Dalarne (54). 

The detection and determination ot the perchlorates.—The perchlorates give no precipitates with silver nitrate or barium chloride soln. cone. soln. give a white crystalline precipitate with potassium chloride. Unlike all the other oxy-acids of chlorine, a soln. of indigo is not decolorized by perchloric acid, even after the addition of hydrochloric acid and they do not give the explosive chlorine dioxide when warmed with sulphuric acid unlike the chlorates, the perchlorates are not reduced by the copper-zinc couple, or sulphur dioxide. Perchloric acid can be titrated with —iV-alkali, using phenolphthalein as indicator. The perchlorates can be converted into chlorides by heat and the chlorides determined volumetrically or gravimetrically they can be reduced to chloride by titanous sulphate 28 and titration of the excess of titanous sulphate with standard permanganate they can be fused with zinc chloride and the amount of chlorine liberated can be measured in terms of the iodine set free from a soln. of potassium iodide and they can be... 

Diphenyl-diacetylene is the parent hydi ocarhon of indigo blue, and the dye itself can be prepared by means of tliis reaction, starting with o-nitro-phenyl-propiolic acid. By loss of carbon dioxide the acid becomes o-nitro-phenyl-acetylene, the copper derivative of which passes to di-ortho-nitrophenyl-diacety-lene ... 

Fig. 36. Iron fusion kettle with copper oil bath for use in primuline, indigo, and alkali fusions, etc. Capacity, about 450 cc.

The blue in the Mameluke carpet easily was identified as indigo by the vatting test. In the yellow and the green threads (after removing the indigo by extraction with N,N-dimethylformamide), I identified a hydroxyflavone dye containing luteolin as the main component, in all probability dyer s rocket, by comparison with the tin, aluminum, iron, copper, and uranyl lakes. 

In a recent industrial application, the multicathode cell of Heraus [59] is used for the indirect reduction of dispersed indigo during a dyeing process [60] (Scheme 2). An iron(II)-triethanolamine complex is the active reducing species. The cathodes consist of folded layers of stainless steel or copper. Graphite felt can also be used for this purpose [61]. The outline of this multicathode cell process is shown in Fig. 6. 

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