We transform commodities into money of account, in our mind, on paper, in conversation, whenever it is a question of expressing any kind of wealth in terms of exchange value.[45] For that transformation we need the gold substance, but only in imagination. In order to estimate the value of a thousand bales of cotton in a certain number of ounces of gold and then to express this number of ounces in the denominations of the ounce, £. s. d., not a single atom of gold is required. Thus, not a single ounce of gold was in circulation in Scotland before Robert Peel’s Bank Act of 1845, although the gold ounce, expressed in its English standard of account, 3£ 17s. 10-1/2d., served as the legal standard of price. In a similar manner silver serves as standard of price in the trade between Siberia and China, although that trade virtually amounts to barter. It is, therefore, immaterial to money, as money of account, whether or not its entire unit of measure or the fractions thereof are really coined. In England, at the time of William the Conqueror, 1£, then a pound of pure silver, and the shilling, 1-20 of a pound, existed only as money of account, while the penny, 1-240 of a pound of silver, was the largest silver coin in existence. On the other hand, there are no shillings and pence in England to-day, although they are legal denominations for certain parts of an ounce of gold. Money as money of account may exist exclusively in idea, while the money in actual existence may be coined according to an entirely different standard. Thus the money in circulation in many English colonies of North America consisted until late in the eighteenth century of Spanish and Portuguese coins, although the money of account was throughout the same as in England.[46]