Paris Green is an
inorganic compoundInorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
more precisely known as copper(II) acetoarsenite. It is a highly toxic emerald-green crystalline powder that has been used as a rodenticide and
insecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
, and also as a pigment, despite its toxicity. It is also used as a blue colorant for fireworks. The color of Paris Green is said to range from a pale, but vivid, blue green when very finely ground, to a deeper true green when coarsely ground.
Preparation
Paris Green may be prepared by combining
copper(II) acetateCopper acetate, also referred to as cupric acetate, is the chemical compound with the formula Cu2 where OAc- is acetate . The hydrated derivative, which contains one molecule of water for each Cu atom, is available commercially. Anhydrous Cu2 is a dark green crystalline solid, whereas Cu22 is...
and
arsenic trioxideArsenic trioxide is the inorganic compound with the formula As2O3. This commercially important oxide of arsenic is the main precursor to other arsenic compounds, including organoarsenic compounds. Approximately 50,000 tonnes are produced annually...
.
Insecticide
Paris Green was once used to kill rats in
ParisParis is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
ian sewers, hence the common name. It was also used in America and elsewhere as an
insecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
for produce, such as
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
s, around 1900, where it was blended with lead arsenate. This quite toxic mixture is said to have burned the trees and the grass around the trees. Paris green was heavily sprayed by airplane in Italy, Sardinia, and Corsica during 1944 and in Italy in 1945 to control malaria.
Pigment
Paris Green was once a popular pigment used in artists' paints.
Related pigments
Similar natural compounds are the minerals
ChalcophylliteChalcophyllite is a rare secondary copper arsenate mineral occurring in the oxidized zones of some arsenic-bearing copper deposits. It was first described from material collected in Germany...
Cu
18Al
2(AsO
4)
3(SO
4)
3(OH)
27·36(H
2O),
ConichalciteConichalcite, CaCu, is a relatively common arsenate mineral related to duftite . It is green, often botryoidal, and occurs in the oxidation zone of some metal deposits. It occurs with limonite, malachite, beudantite, adamite, cuproadamite, olivenite and smithsonite.- Formation :Conichalcite forms...
CaCu(AsO
4)(OH),
CornubiteCornubite is a rare secondary copper arsenate mineral with formula: Cu524. It was first described for its discovery in 1958 in Wheal Carpenter, Gwinear, Cornwall, England, UK. The name is from Cornubia, the medieval Latin name for Cornwall...
Cu
5(AsO
4)
2(OH)
4·(H
2O), Cornwallite Cu
5(AsO
4)
2(OH)
4·(H
2O), and
LiroconiteLiroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula Cu2Al[4|AsO4]·4. It is a vitreous monoclinic mineral, colored bright blue to green, often associated with malachite, azurite, olivenite, and clinoclase...
Cu
2Al(AsO
4)(OH)
4·4(H
2O). These vivid minerals range from greenish blue to slightly yellowish green.
Scheele's greenScheele's Green, also called Schloss Green, is chemically a cupric hydrogen arsenite , CuHAsO3. It is a compound similar to Paris Green...
is a chemically simpler, less brilliant, and less permanent, synthetic copper-arsenic pigment used for a rather short time before Paris Green was first prepared, which was approximately 1814. It was popular as a
wallpaperWallpaper is a kind of material used to cover and decorate the interior walls of homes, offices, and other buildings; it is one aspect of interior decoration. It is usually sold in rolls and is put onto a wall using wallpaper paste...
pigment, and would degrade, with moisture and moulds, to
arsineArsine is the chemical compound with the formula AsH3. This flammable, pyrophoric, and highly toxic gas is one of the simplest compounds of arsenic...
gas. Paris Green may have also been used in wallpaper to some extent and may have also degraded similarly. Both pigments were once used in
printingPrinting is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing....
inkInk is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
formulations.
The
ancient RomansAncient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....
used one of them, possibly conichalcite, as a green pigment. The Paris Green paint used by the Impressionists is said to have been composed of relatively coarse particles. Later, the chemical was produced with increasingly small grinds and without carefully removing impurities; its permanence suffered. It is likely that it was ground more finely for use in watercolors and inks, too.
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