60 Minims (Minimum) (M. or Ms.) = 1 Fluid Drachm.
8 Fluid Drachms (Fluid Drachma) (fl. ʒ) = 1 Fluid Ounce.
16 Fluid Ounces (Fluid Uncia) (fl. ℥) = 1 Pint.
2 Pints (Octarius) (O.) = 1 Quart.
4 Quarts or 8 Pints = 1 Gallon (congius--C.)
In prescribing liquids the abbreviation for Quarts (Qts.) is never used.
If a quart is desired it is expressed as two pints (Oij).