The Department of Edible Weights and Standards

How do you measure tiny weights? It was a serious question before high-tech weighing devices were available because things you’d want to measure in very small quantities tend to be expensive, such as precious metals--or, in the Middle Ages, spices. In the old days, people usually picked either coins or edible seeds as the weighing standard because they were available everywhere and presumably of a standard weight.

Coins had the advantage that they wouldn’t go bad on you by sprouting, but they were treacherous because governments were always debasing their currency--wriggling out of their debts by cutting the amount of precious metal they put in their coins. A Venetian gold coin called the zecchino ended up so flimsy you could punch a hole in it. In fact, people took to doing exactly that and decorating their clothes with zecchinos, and that’s where we get the word “sequin” (which no longer refers to a coin, of course).

The Greeks and Romans, like the people of the Middle East, used coins such as the drachma as a weight, but their basic units were wheat and barley grains, and we still sometimes measure small quantities of things like medicines in weights called grains. The ancient Greeks also used the carob seed, which was conveniently presumed to equal the weight of four wheat grains or three barleycorns. Their word for it was keration, which passed through Arabic to become our word “carat.”