Prussian blue: Difference between revisions
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Despite the presence of the [[cyanide]] [[ion]], Prussian Blue, like other ferro- and ferri-cyanides, is not especially toxic due to the strong binding between the cyanide and ferrous or ferric (iron) ions. However, treatment with [[acid]]s can liberate the cyanide in the form of [[hydrogen cyanide]], which is extremely [[toxic]]. |
Despite the presence of the [[cyanide]] [[ion]], Prussian Blue, like other ferro- and ferri-cyanides, is not especially toxic due to the strong binding between the cyanide and ferrous or ferric (iron) ions. However, treatment with [[acid]]s can liberate the cyanide in the form of [[hydrogen cyanide]], which is extremely [[toxic]]. |
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Because of the above mentioned there is a [[controversy]] among pseudo-scientists trying to disprove the [[holocaust]]. It is a common argument that because the levels of cyanide (Prussian blue) are higher on the walls of the delousing chambers than the homicide chambers, the homicide chambers were not used to any extent. Anyone that understands the properties of iron bonded cyanide and cyanide gas can easily refute this. |
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Revision as of 11:39, 31 July 2005
Prussian blue is a dark blue pigment used in paints and formerly in blueprints. It has several different chemical names, these being iron(III) ferrocyanide, ferric ferrocyanide, iron(III) hexacyanoferrate(II), and ferric hexacyanoferrate. Prussian Blue is a strong color, and tends towards black and dark purple when mixed with other oil paints.
The chemical formula is Fe4[Fe(CN)6]3.
Prussian blue can also act as a chelating agent, and is used as a treatment for heavy metals poisoning. In particular, it is used for patients who have ingested radioactive caesium or thallium (also non-radioactive thallium).
The intense blue color of Prussian Blue is caused by the transfer of electrons from one iron atom to another within the molecule. 680 nm (red) light is absorbed, causing an electron to transfer from an Fe(II) atom to a neighboring Fe(III) atom. The reflected light looks blue as a result.
Suspended as a colloid in water, Prussian Blue is the basis for laundry bluing. As engineer's blue it is mixed with an oily material, and rubbed onto a metallic surface. This is then rubbed with another surface, and the removal of the pigment indicates the position of high-spots. Thus it can be used to indicate the flatness of a surface or the trueness of a bearing assembly.
Joseph Whitworth invented the first practical method of making and polishing accurate flat surfaces in 1830. This used engineer's blue and three trial surfaces. This led to an explosion of development of precision instruments using his flat surfaces as a basis for further construction of precise shapes.
Despite the presence of the cyanide ion, Prussian Blue, like other ferro- and ferri-cyanides, is not especially toxic due to the strong binding between the cyanide and ferrous or ferric (iron) ions. However, treatment with acids can liberate the cyanide in the form of hydrogen cyanide, which is extremely toxic.
See also
External links
- http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202737.html (note: this is not in the public domain, even though it is on a .gov site)
- The FDA's page on prussian blue: http://www.fda.gov/cder/drug/infopage/prussian_blue/Q&A.htm