The drachma is the eighth part of an ounce, and the weight of the silver denarius containing three scripula.
Solidus apud Latinos alio nomine ‘sextula’ dicitur, quod his sex uncia compleatur; hunc, ut diximus, vulgus aureum solidum vocat, cujus tertium partem ideo dixerunt tremissem.[133]
The solidus with the Romans is otherwise called the sextula because it is one sixth of the ounce; hence, as we have said, the vulgar call the solidus the aureus, the third part of which is called the tremissis.
Thus the solidus was the typical gold unit or aureus, and the drachma was the silver denarius or argenteus.
Twelve drachmas of silver = at 1:10 the Merovingian gold solidus.
It is remarkable that at a ratio of 1:10 twelve Wisigothic or Roman argentei or drachmas of silver equalled exactly in wheat-grains the Merovingian gold solidus current on the Frankish side of the Garonne or the Loire.[134]
It would seem, then, probable that traditionally and ‘according to ancient custom’ outside the Frankish kingdom the Merovingian gold solidus had been equated with twelve silver argentei or denarii of this reckoning, whilst within Frankish limits 40 of the silver tremisses and now of the pence of the nova moneta were reckoned as equal to the gold solidus of the Lex Salica.
But even to the Frank the 40 denarii of the Lex Salica may have become antiquated except for wergelds and other payments under its provisions.
The silver solidus of 12 silver tremisses already in use in accounts, as 1/20 of the pound of silver of 240 pence.