The dram is a unit of mass in the avoirdupois system, and both a unit of mass and a unit of volume in the apothecaries' system. It was originally both a coin and a weight in ancient Greece. The unit of volume is more correctly called a fluid dram, fluid drachm, fluidram or fluidrachm.
Silver Drachm from Dyrrhachium, Illyria dated c. 229 BC. Obverse: ΞΕΝΩΝ (Xenon) cow standing right, looking back at calf which it suckles, eagle standing right above; Reverse: DUR PURBA, square containing double stellate pattern, club to left. Size: 20mm; Reference: Ceka 360
A "wee dram", in Scotland the 35 ml measurement.
The apothecaries' system, or apothecaries' weights and measures, is a historical system of mass and volume units that were used by physicians and apothecaries for medical prescriptions and also sometimes by scientists. The English version of the system is closely related to the English troy system of weights, the pound and grain being exactly the same in both. It divides a pound into 12 ounces, an ounce into 8 drachms, and a drachm into 3 scruples of 20 grains each. This exact form of the system was used in the United Kingdom; in some of its former colonies, it survived well into the 20th century. The apothecaries' system of measures is a similar system of volume units based on the fluid ounce. For a long time, medical recipes were written in Latin, often using special symbols to denote weights and measures.
German postage stamp from 1991, commemorating 750 years of the apothecary profession
