Convert from tonneau [France] to fotmal [lead]

Unit Definition (tonneau [France])
The tonneau is the traditional French ton, equal to 2000 livres or about 979 kilograms (1.079 U.S. ton). The tonneau was also used as a measure of volume equal to 42 cubic pieds (50.84 cubic feet, or about 1440 liters). In the wine trade, the tonneau was a shipment of 100 cases, or 1200 bottles (about 900 liters of wine).

Unit Definition (fotmal [lead])
The fotmal is a traditional English unit of weight for lead. In medieval England the fotmal was equal to 70 "mercantile" pounds, which is equivalent to 72 avoirdupois pounds.