Editing Potassium ferrocyanide (section)

==Applications==
Potassium hexacyanidoferrate(II) finds many niche applications in industry.  It and [[Sodium ferrocyanide|the related sodium salt]] are widely used as anticaking agents for both road salt and table salt. The potassium and sodium hexacyanidoferrates(II) are also used in the purification of tin and the separation of copper from molybdenum ores.  Potassium hexacyanidoferrate(II) is used in the production of wine and citric acid.<ref name=Ullmann/>

In the EU, hexacyanidoferrates(II) (E 535–538) were, as of 2017, solely authorised in two food categories as salt additives.

It can also be used in animal feed.<ref>{{cite web |title=EuSalt Expert Meeting on E 535 and E 536 as Feed Additives |url=https://eusalt.com/events/eusalt-expert-meeting-e-535-and-e-536-feed-additives |publisher=EUSalt |access-date=2018-12-06 |archive-date=2019-05-12 |archive-url=https://web.archive.org/web/20190512013808/https://eusalt.com/events/eusalt-expert-meeting-e-535-and-e-536-feed-additives |url-status=dead }}</ref>

In the laboratory, potassium hexacyanidoferrate(II) is used to determine the concentration of [[potassium permanganate]], a compound often used in [[titration]]s based on [[redox]] reactions.  Potassium hexacyanidoferrate(II) is used in a mixture with potassium ferricyanide and phosphate buffered solution to provide a buffer for [[beta-galactosidase]], which is used to cleave [[X-Gal]], giving a bright blue visualization where an antibody (or other molecule), conjugated to Beta-gal, has bonded to its target. On reacting with Fe(3) it gives a Prussian blue colour. Thus it is used as an identifying reagent for iron in labs.

Potassium hexacyanidoferrate(II) can be used as a fertilizer for plants.<ref name="ejk" />

Prior to 1900, before the invention of the [[Castner process]], potassium hexacyanidoferrate(II) was the most important source of [[alkali metal]] [[Sodium cyanide|cyanides]].<ref name=Ullmann /> In this historical process, [[potassium cyanide]] was produced by decomposing potassium hexacyanidoferrate(II):<ref name=Wagner />

K<sub>4</sub>[Fe(CN)<sub>6</sub>] → 4 KCN + FeC<sub>2</sub> + N<sub>2</sub>

Potassium ferrocyanide is a component of ''white gunpowder'' or ''Augendre's powder'', a [[blasting powder]] of high energy.<ref>{{cite book |last1=Fay |first1=Albert |title=A Glossary of the Mining and Mineral Industry |date=1918 |publisher=[[United States Bureau of Mines]] |location=Washington, DC |page=741 |edition=1949}}</ref> It comprises 28 parts yellow potassium ferrocyanide, 23 parts cane sugar, and 49 parts of [[potassium chlorate]], mixed under [[absolute alcohol]] to prevent premature detonation.<ref>{{cite book |last= |first= |date= |title=Chemischen Technologie |url= |trans-title=A Handbook of Chemical Technolgie|language=German |translator-last1=Crookes |translator-first1=Willliam |translator-link1=William Crookes|location=New York |publisher=[[D. Appleton & Company]] |page= 155|edition=1872}}</ref><ref>{{cite book |last1=Brannt |first1=William T. (William Theodore) |last2=Wahl |first2=William H. (William Henry) |title=The Techno-chemical receipt book |date=1919 |publisher=Henry Carey Baird & Co. |location=New York |page=30 |url=https://archive.org/details/technochemicalre00bran/page/30/mode/1up}}</ref>