Herapathite
Encyclopedia
Herapathite, or iodoquinine
sulfate
, is a chemical compound
whose crystal
s are dichroic
and thus can be used for polarizing light.
According to Edwin H. Land
, it was discovered in 1852 by William Bird Herapath, a doctor
in Bristol
. One of his pupils found that adding iodine
to the urine
of a dog that had been fed quinine
produced unusual green crystals. Herapath noticed while studying the crystals under a microscope
that they appeared to polarize light.
Prof. Ferdinand Bernauer invented a process to grow single herapathite crystals large enough to be sandwiched between two sheets of glass to create a polarizing filter.
These were sold under the Bernotar name by Carl Zeiss
.
This method has since been lost.
Herapathite's dichroic properties came to the attention of Sir David Brewster
, and were later used by Land in 1929 to construct the first type of Polaroid sheet polarizer. He did this by embedding herapathite crystals in a polymer instead of growing a single large crystal.
For hypothetical crystal structure see A.M. Marks.
Crystal structure recently reported in Science Magazine.
Quinine
Quinine is a natural white crystalline alkaloid having antipyretic , antimalarial, analgesic , anti-inflammatory properties and a bitter taste. It is a stereoisomer of quinidine which, unlike quinine, is an anti-arrhythmic...
sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
, is a chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
whose crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
s are dichroic
Dichroism
Dichroism has two related but distinct meanings in optics. A dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths , or one in which light rays having different polarizations are absorbed by different amounts.The original meaning of...
and thus can be used for polarizing light.
According to Edwin H. Land
Edwin H. Land
Edwin Herbert Land was an American scientist and inventor, best known as the co-founder of the Polaroid Corporation. Among other things, he invented inexpensive filters for polarizing light, a practical system of in-camera instant photography, and his retinex theory of color vision...
, it was discovered in 1852 by William Bird Herapath, a doctor
Physician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...
in Bristol
Bristol
Bristol is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone with an estimated 1,070,000 residents in 2007...
. One of his pupils found that adding iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
to the urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
of a dog that had been fed quinine
Quinine
Quinine is a natural white crystalline alkaloid having antipyretic , antimalarial, analgesic , anti-inflammatory properties and a bitter taste. It is a stereoisomer of quinidine which, unlike quinine, is an anti-arrhythmic...
produced unusual green crystals. Herapath noticed while studying the crystals under a microscope
Microscope
A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...
that they appeared to polarize light.
Prof. Ferdinand Bernauer invented a process to grow single herapathite crystals large enough to be sandwiched between two sheets of glass to create a polarizing filter.
These were sold under the Bernotar name by Carl Zeiss
Carl Zeiss
Carl Zeiss was a German maker of optical instruments commonly known for the company he founded, Carl Zeiss Jena . Zeiss made contributions to lens manufacturing that have aided the modern production of lenses...
.
This method has since been lost.
Herapathite's dichroic properties came to the attention of Sir David Brewster
David Brewster
Sir David Brewster KH PRSE FRS FSA FSSA MICE was a Scottish physicist, mathematician, astronomer, inventor, writer and university principal.-Early life:...
, and were later used by Land in 1929 to construct the first type of Polaroid sheet polarizer. He did this by embedding herapathite crystals in a polymer instead of growing a single large crystal.
For hypothetical crystal structure see A.M. Marks.
Crystal structure recently reported in Science Magazine.