Herapathite
Chininiodsulfat hexahydrate
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Herapathite is a chemical compound having polarizing properties.
History
Herapathite in 1852 by the English physician and researcher William Bird Herapath ( 1820-1868 ) discovered in an unusual way. In a biological test his assistant iodine tincture dripped in dog urine after this before quinine was administered. It formed in the dog's urine green, shimmering, needle-shaped crystals, which aroused the interest of the researcher. He put in investigations under the microscope strong polarization properties of the substance found what he concluded from the black coloration when the crystals are covered in certain angles. The chemical structure was elucidated in 1876 by Sophus Joergensen. Named after its discoverer connection is used for the production of polarization filters. Initial problems to small size of the crystals was improved crystal growth process ( so after Ferdinand Bernauer, who succeeded to breed large, but only a fraction of a millimeter thick single crystals ) or be countered by processes at the same dichroic orientation of a large number of small crystals. So in the 1930s, the American physicist Edwin Herbert Land polarizing films developed from stretched plastic films ( which is also the molecules of the plastic lined up parallel ) passed with embedded Herapathitkristallen. This polarization filter can still be found in photography, but also in sunglasses, use. The patent for this technology was the physicist issued in 1933, which a little later named after the film company founded Polaroid. During the same period the orthorhombic crystal structure was determined by Charles West. But it was only in 2009, chemists from the University of Washington in Seattle have decoded the exact structure of herapathite by X-ray diffraction analyzes.
Properties
Chemically, it is at herapathite to Chininsulfatperiodit (or Iodchininsulfat or Chininbisulfatpolyiodid or Chininhydrogensulfatpolyiodid ) with the chemical formula 4 · ( C20H24N2O2 ) · H2 · 3 · (SO4) · 2 · (I3 ) · 6 · (H2O ), with several used to produce various crystals with these components by the different oxidation states of iodine, but all have similar characteristics as herapathite. Herapathite is produced by solution of sulphate of quinine in acetic acid with the addition of iodine. However, the emergent needle-shaped crystals are colorless, in reflected light lush green metallic luster. Herapathite is sparingly soluble in water and slightly soluble in alcohols. It polarized light five times stronger than tourmaline and used in polarizing filters. The color properties of the dichroic material caused by iodide anion chains.