Imperial and US customary measurement systems different concepts – the imperial gallon is defined in terms of the volume occupied by a specified mass of water, while the US gallon is specified in terms of cubic linear measure. Notes Notes Units of weight in both the imperial and US customary system always used the same standard, though differences in multiples of the avoirdupois pound developed in the nineteenth century. Both systems used the three different scales – the avoirdupois system for general use, the troy system for precious metals and the apothecaries system in the pharmacy industry. The term "weight" and "mass" are used interchangeably in
Mithqal Mithqal Mithqāl () is a unit of mass equal to 4.5 grams which is mostly used for measuring precious metals, such as gold, and other commodities, like saffron. The name was also applied as an alternative term for the gold dinar, a coin that was used throughout much of the Islamic world from the 8th century onward and survived in parts of Africa until the 19th century. The name of Mozambique's currency since 1980, the "metical", is derived from "mithqāl". The word "mithqāl" (; “weight, unit of weight”) comes from the Arabic "thaqala" (), meaning “to weigh”. Other variants of