Apothecaries' Dram (ʒ)

Troy & apothecaries'Historical unit (no longer in standard use)

60 grains or 3 scruples (3.888 g). Used in old medical prescriptions.

1 apothecaries' dram = 0.0038879346 kilograms (exactly).

About the apothecaries' dram

Greek drachma coins left their mark on this unit, which the apothecaries' tables spelled drachm or dram and abbreviated with a curled symbol. It was worth 60 grains, or three scruples, or about 3.89 grams, and eight of them filled an apothecaries' ounce.

Doctors wrote it into Latin prescriptions with Roman numerals, so three drams appeared as the symbol followed by iij and half a dram as the symbol followed by ss, short for semis. Until about 1900 most prescriptions were written this way.

Do not confuse it with the avoirdupois dram, which is much smaller than this one, and with the fluid dram used for liquids. An Irish pharmacopoeia of 1850 even proposed an avoirdupois-based version of about 54.68 grains. British law ended the apothecaries' system in the 1970s, and modern doses are given in grams or milligrams.

Sources: Wikipedia: Apothecaries' system; Wikipedia: Troy weight

Apothecaries' Dram conversion chart

1 apothecaries' dram expressed in every other weight & mass unit:

More Troy & apothecaries' units

• troy ounce (weight & mass)
• troy pound (weight & mass)
• pennyweight (weight & mass)
• scruple (weight & mass)

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