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
Trade during the Viking Age so there was no danger of them being rearranged or switched during the course of an exchange. Estimated exchange rates at the beginning of the 11th century in Iceland were: If the weight of a piece of jewelry was more than needed to complete a purchase, it was cut up into smaller bits until the correct weight needed for the transaction was reached. The term hack silver is used to describe these silver objects. Silver ingots were primarily used for large/high-value transactions. The largest found weights weigh more than 1 kilogram each. Precious metals were also used to display personal