of Europe the scruple was divided in 24 grains, in the rest of Europe in 20 grains. Notable exceptions were Venice and Sicily, where the scruple was also divided in 20 grains. The Sicilian apothecaries ounce was divided into 10 drachms. Since the scruple was divided into only 20 grains, like in the northern countries, an ounce consisted of 600 grains. This was not too different from the situation in most of the other Mediterranean countries, where an ounce consisted of 576 grains. In France, at some stage the apothecaries' pound of 12 ounces was replaced by the larger civil pound of 16 ounces. The subdivisions of the apothecaries ounce were the same as in the other Romance countries, however, and were different from the subdivisions of the otherwise identical civil ounce. Origins Roman weight system The basic apothecaries' system consists of the units pound, ounce, and scruple from the classical Roman weight system, together with the originally Greek drachm and a new subdivision of the scruple into either 20 ("barley") or 24 ("wheat") grains (). In some countries other units of the original system remained in use, for example in Spain the and . In some cases the apothecaries' and civil weight systems had the same ounces ("an ounce is an ounce"), but the civil pound consisted of 16 ounces. is Latin for the seed of the carob tree. Many attempts were made to reconstruct the exact mass of the Roman pound. One method for doing this consists in weighing old coins; another uses the fact that Roman weight units were derived from Roman units of length similar to the way the kilogramme was originally derived from the metre, i.e. by weighing a known volume of water. Nowadays the Roman pound is often given as 327.45 g, but one should keep in mind that (apart from the other uncertainties that come with such a reconstruction) the Roman weight standard is unlikely to have remained constant to such a precision over the centuries, and that the provinces often had somewhat inexact copies of the standard. The weight and subdivision of the pound in the Holy Roman Empire were reformed by Charlemagne, but in the Byzantine Empire it remained essentially the same. Since Byzantine coins circulated up to Scandinavia, the old Roman standard continued to be influential through the Middle Ages. Weight system of Salerno The history of mediaeval medicine started