Brilliant indigo

Amido-azo-benzene Amido-azo-toluene Aniline black Auramine Bismarck brown Brilliant indigo, 4 G. 

Indium and thallium were also discovered by means of the spectroscope as their names indicate. Indium was first identified in 1863 by F. Reich and H. T. Richter and named from the brilliant indigo blue line in its fiame spectrum (Latin indicum). Thallium was discovered independently by W. Crookes and by... 

Hieronymus Theodor Richter was bom at Dresden on November 21, 1824. He became a metallurgical chemist at the Freiberg School of Mines. When he placed some of the zinc blende in the loop of a platinum wire and heated it in the flame of a Bunsen burner, he observed a brilliant indigo line which did not coincide with either of the blue lines of cesium (20, 52). Because of this characteristic spectral line the new element was christened indium. The publication of this contribution under joint authorship was a mistake which Professor Reich afterward regretted, for Richter tried to make it appear that he Was the sole discoverer (2, 51, 52). 

Reich and Richter found later that there are two indium lines, the brighter one being slightly more refrangible than the blue line of strontium, and the weaker one still more refrangible and located near the blue line of calcium. Indium compounds impart such a brilliant indigo-violet color to the Bunsen flame that they can be recognized even without a spectroscope. 

Chloronitrotoluene and 2,6-chlorotoluidine are technically important in other respects also. The former compound is the starting material for the prepara-oitn of 4,4 -dichloroindigo, which yields, on further chlorination or bromination, the very greenish 4,5,4, 5 -tetrahalogenindigos (e.g., brilliant indigo 4G). 2,6-Chloro-toluidine, as fast scarlet TR base, is used in generating ice colors (naphthol AS). The isomeric 4-chloro-2-toluidine (fast red KB base), prepared by reduction of the by-product 4-chloro-2-nitrotoluene, is used for the same purpose. 

Reich and Richter suggested the name indium for the element they discovered because its main spectral lines are a brilliant indigo blue. 

Indium — (from the brilliant indigo line in its spectrum). In at. wt. 114.818(3) at. no. 49 m.p. 156.60°C b.p. 2072°C sp. gr. 7.31 (20°C) valence 1,2, or 3. Discovered by Reich and Richter, who later isolated the metal. Indium is most frequently associated with zinc materials, and it is from these that most commercial indium is now obtained however, it is also found in iron, lead, and copper ores. Until 1924, a gram or so constituted the world s supply of this element in isolated form. It is probably about as abundant as silver. About 4 million troy ounces of... 

Indium (In) was first isolated by Ferdinand Reich in 1836. However, he was color blind and confused the brilliant indigo spectral color of indium with thallium. Indium was later identified by Hieronymus Richter in 1863 as part of ZnS, a mineral called zinc blende. 

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