The golden Dinar, 21-3/4 qirát, was of the weight of the Attic commercial drachma = 65·6 grains; it displaced the Roman golden denarius. But the lesser dirhem, 2/3 the weight of the Mithkal, did not succeed in displacing an old-established drachma, which became a greater dirhem. For, as the Mithkal had a dirhem 2/3 of its weight, so the Roman Aureus, 1/6 of the As-ounce, had a silver drachma 3/4 of its weight. The As, originally 1/100 of the Greek-Asiatic talent, had its ounce divided, after the Greek system, into 8 drachmæ each 5049/(12 × 8) = 52·6 grains. Apparently this _greater dirhem_ tended, in Arab times, to fall towards the standard of the lesser dirhem = 48·5 grains. This is the probable explanation of the variations of the dirhems, and of the pounds based on them, along the Mediterranean coasts.
In Tunis the dirhem = 48·58, almost exactly the original weight of the lesser dirhem. But in Tripoli there are two standards, 47·075 and 50·1 grains. The Ukyé or ounce is goldsmith’s weight, 10 dirhems of 47·075 grains; but in commercial weight it is in dirhems of 50·1 grains, so it is made the same weight by reckoning it as 150 kharūb or qirát instead of 160 of these as in the goldsmith’s ounce of 10 dirhems of 16 qirát.
So there are variations in the weight of the dirhem basis of the Mediterranean pounds:
In Egypt the dirhem = 47·66 grains In Tripoli „ = ⎧47·07 „ ⎩50·1 „ In Tunis „ = 48·58 „ In Morocco „ = 49 „ In Turkey „ = 49·6 „
The qirát, 1/16 of the dirhem, varies with it.
The Oka, = 2·723 lb., is 400 dirhems of 47·66 grs.
The Rottolo, = 98 lb., is 144 dirhems of 47·66 grs.
The Oka is a centesimal multiple of the dirhem.
100 Rottoli = 1 Cantar = 98 lb.; this is the modern Egyptian Cwt. which has succeeded the Cantar of Al-Mamūn = 102·92 lb.
There is a double series as in Egypt, but the Turkish series are based, one on the Dirhem and the other on the Egypto-Roman ounce at the standard of 436·45 grains. In modern Rome it is 436·26 grains, in Tuscany 436·66 grains.
The Dirhem, = 49·5 grains, is 16 qirát of 3·1 grains.
The Cheké is of 100 dirhems = 4950 grains.
The Cantar is = 2000 ounces = 124·7 or 44 Oke.
The Cantar is divided into 100 Rottoli of 1·247 lb., = 20 ounces.