> Every traded object had its own measurement system

In US commodities it kind of still does: they're measured in "bushels" but it's now a unit of weight. And it's a different weight for each commodity based on the historical volume. http://webserver.rilin.state.ri.us/Statutes/TITLE47/47-4/47-...

The legal weights of certain commodities in the state of Rhode Island shall be as follows:

(1) A bushel of apples shall weigh forty-eight pounds (48 lbs.).

(2) A bushel of apples, dried, shall weigh twenty-five pounds (25 lbs.).

(3) A bushel of apple seed shall weigh forty pounds (40 lbs.).

(4) A bushel of barley shall weigh forty-eight pounds (48 lbs.).

(5) A bushel of beans shall weigh sixty pounds (60 lbs.).

(6) A bushel of beans, castor, shall weigh forty-six pounds (46 lbs.).

(7) A bushel of beets shall weigh fifty pounds (50 lbs.).

(8) A bushel of bran shall weigh twenty pounds (20 lbs.).

(9) A bushel of buckwheat shall weigh forty-eight pounds (48 lbs.).

(10) A bushel of carrots shall weigh fifty pounds (50 lbs.).

(11) A bushel of charcoal shall weigh twenty pounds (20 lbs.).

(12) A bushel of clover seed shall weigh sixty pounds (60 lbs.).

(13) A bushel of coal shall weigh eighty pounds (80 lbs.).

(14) A bushel of coke shall weigh forty pounds (40 lbs.).

(15) A bushel of corn, shelled, shall weigh fifty-six pounds (56 lbs.).

(16) A bushel of corn, in the ear, shall weigh seventy pounds (70 lbs.).

(17) A bushel of corn meal shall weigh fifty pounds (50 lbs.).

(18) A bushel of cotton seed, upland, shall weigh thirty pounds (30 lbs.).

(19) A bushel of cotton seed, Sea Island, shall weigh forty-four pounds (44 lbs.).

(20) A bushel of flax seed shall weigh fifty-six pounds (56 lbs.).

(21) A bushel of hemp shall weigh forty-four pounds (44 lbs.).

(22) A bushel of Hungarian seed shall weigh fifty pounds (50 lbs.).

(23) A bushel of lime shall weigh seventy pounds (70 lbs.).

(24) A bushel of malt shall weigh thirty-eight pounds (38 lbs.).

(25) A bushel of millet seed shall weigh fifty pounds (50 lbs.).

(26) A bushel of oats shall weigh thirty-two pounds (32 lbs.).

(27) A bushel of onions shall weigh fifty pounds (50 lbs.).

(28) A bushel of parsnips shall weigh fifty pounds (50 lbs.).

(29) A bushel of peaches shall weigh forty-eight pounds (48 lbs.).

(30) A bushel of peaches, dried, shall weigh thirty-three pounds (33 lbs.).

(31) A bushel of peas shall weigh sixty pounds (60 lbs.).

(32) A bushel of peas, split, shall weigh sixty pounds (60 lbs.).

(33) A bushel of potatoes shall weigh sixty pounds (60 lbs.).

(34) A bushel of potatoes, sweet, shall weigh fifty-four pounds (54 lbs.).

(35) A bushel of rye shall weigh fifty-six pounds (56 lbs.).

(36) A bushel of rye meal shall weigh fifty pounds (50 lbs.).

(37) A bushel of salt, fine, shall weigh fifty pounds (50 lbs.).

(38) A bushel of salt, coarse, shall weigh seventy pounds (70 lbs.).

(39) A bushel of timothy seed shall weigh forty-five pounds (45 lbs.).

(40) A bushel of shorts shall weigh twenty pounds (20 lbs.).

(41) A bushel of tomatoes shall weigh fifty-six pounds (56 lbs.).

(42) A bushel of turnips shall weigh fifty pounds (50 lbs.).

(43) A bushel of wheat shall weigh sixty pounds (60 lbs.).