by Venerable Dr I. U. Ibeme
KANWA (or AKANWU) is the local Nigerian name for:
- Crystal Soda (SODA is crystallised hydrous carbonate of sodium and of two types, either as carbonate Na2CO3.Na2CO3.2H2O called TRONA or as bicarbonate Na2CO3.NaHCO3.2H2O called NATRON and powdery anhydrous carbonate of sodium Na2CO3 i.e. SODA ASH). These are the main constituents of Kanwa; and
- Crystal Potash (granular POTASH is the crystallised hydrous carbonate of potassium K2CO3.H2O; similar in composition with powdery anhydrous PEARL ASH K2CO3).
In Nigeria people do not usually distinguish between common greyish-white Crystal Soda Kanwa (i.e. Trona and Natron) and the rare yellowish-white Crystal Potash Kanwa (i.e. Potash); all are commonly thought to be ‘potash’. Pearl ash is organic Potash locally produced from burnt wood and plant ashes, while mineral Potash is industrially produced form Solvay process which chemically treats common salt solution with ammonia and carbon dioxide or from Engel-Precht process. The naturally occurring Kanwa mineral varieties (Trona, Natron and Potash) usually contain several other impurities such as sand, clay, and metals like, silicon, magnesium, calcium, iron, aluminium, and titanium.
All these Kanwa varieties have similar properties. They are all alkaline (soapy) when dissolved in water. They are all used for making tanner’s lye (liquid soap of either caustic potash KOH or caustic soda NaOH) used in tanning leather, for making soap, and for tenderizing, emulsifying and preserving food. At the mining quarries of Kanwa, other minerals may coexist, such as thermonatrite, halite (common salt), thernadite, merabilite, and gypsum.
In the Gastro Intestinal System Kanwa is used for toothache relief, as antacid and stomachic, for relief of constipation and flatulence. Kanwa is also a liver stimulant but in larger doses it irritates the stomach, causing heartburn.
In the Renal System, Kanwa induces alkaline diuresis (i.e. increased urination) and dilates blood vessels to enhance renal blood flow. When taken in excess, the sodium in Kanwa accumulates in the blood causing raised blood pressure.
In the Respiratory System, Kanwa induces secretion of the respiratory mucosa to act as an expectorant.
Generally, Kanwa induces diaphoresis by dilating blood vessels of the skin with subsequent cooling effect that may feel helpful in febrile conditions.
In traditional concoctions and for culinary purposes Kanwa serves as tenderizer, thickener, seasoning, potentiating adjunct and preservative. Ancient Egyptians used natron Kanwa solution as preservative in mummification.
Venerable Dr Ifechukwu U. Ibeme (0802 358 9315)
Chief Medical Officer, Staff Retainership Clinic, UMTH, Maiduguri, Borno State, Nigeria.
Updated May 3, 2012
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