Al-Khazini’s Balance of Wisdom

Abu al-Fath Khazini's "Balance of Wisdom" was one of the most sophisticated and advanced balances to be designed and manufactured in the medieval Islamic world. Hydrostatic balances were used to assess the value of the precious metals and gemstones entering the royal treasury. Al-Khazini presents a detailed description of his balance in Al-Kitab Mizan Al-Hikma. Among the advantages of this instrument were its higher degree of precision, its complex triple action, and its ability to identify and determine the percentage by weight of the constituent elements in a binary alloy, provided one of the elements in the alloy is known. It was also capable of measuring the weight and density of pure metals and alloys with a high degree of accuracy. This paper describes the construction of a prototype of Al-Khazini's balance and the testing of its accuracy in weighing, titration, and the identification of elements following the instructions contained in Al-Kitab Mizan Al-Hikma. The instrument was found to function as accurately as claimed by its inventor.