Name used for various inorganic compounds of potassium, chiefly the carbonate (K2CO3), a white crystalline material formerly obtained from wood ashes. They are used to make special types of glass, potassium silicate (a dehydrating agent), pigments, printing inks, and soft soaps; for washing raw wool; and as a lab reagent and general-purpose food additive. Potassium hydroxide is frequently called caustic potash, and in the fertilizer industry, potassium oxide is called potash.
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Potash has been used since antiquity in the manufacture of glass and soap and as a fertilizer. The name comes from the English words pot and ash, referring to its discovery in the water-soluble fraction of wood ash.
The term has become somewhat ambiguous due to the substitution in fertilizers of cheaper potassium salts, such as potassium chloride (KCl) or potassium oxide (K2O), to which the same common name is now sometimes also applied. In addition, potassium hydroxide (KOH) is commonly called caustic potash, an additional source of confusion.
The element potassium derives its English name from potash. A number of chemical compounds containing potassium use the word potash in their traditional names:
|Common name||Chemical name||Formula|
|Potash fertilizer||potassium oxide||K2O|
|Caustic potash or potash lye||potassium hydroxide||KOH|
|Carbonate of potash, salts of tartar, or pearlash||potassium carbonate||K2CO3|
|Chlorate of potash||potassium chlorate||KClO3|
|Muriate of potash||potassium chloride||KCl|
|Nitrate of potash or saltpeter||potassium nitrate||KNO3|
|Sulfate of potash||potassium sulfate||K2SO4|
|Permanganate of potash||potassium permanganate||KMnO4|
Potash production provided late-18th and early-19th century settlers in North America a way to obtain badly needed cash and credit as they cleared their wooded land for crops. To make full use of their land, excess wood, including stumps, needed to be disposed. The easiest way to accomplish this was to burn any wood not needed for fuel or construction. Ashes from hardwood trees could then be used to make lye, which could either be used to make soap or boiled down to produce valuable potash. Hardwood could generate ashes at the rate of 60 to 100 bushels per acre (500 to 900 m³/km²). In 1790, ashes could be sold for $3.25 to $6.25 per acre ($800 to $1500/km²) in rural New York State – nearly the same rate as hiring a laborer to clear the same area.
Potash along with hartshorn is also used as a baking aid similar to baking soda in old German Christmas bakery receipes such as Lebkuchen (ginger bread).
In 2005, Canada was the largest producer of potash with almost one-fourth of the world share followed by Russia and Belarus in Soligorsk, reports the British Geological Survey. The most significant reserve of Canada's potash is located in the province of Saskatchewan and controlled by the Potash Corporation of Saskatchewan.
The world's third largest potash reserve has been discovered in Udon Thani Thailand. Currently, there is much unrest in the region as Canadian and Thai mining interests are battling a community social movement made up primarily of farmers who fear potash mining may destroy their farmland.