Dram (unit)

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The dram (archaic spelling drachm) was historically both a coin and a weight. Currently it is both a small mass in the avoirdupois system of weights and a small unit of volume. This unit is called more correctly fluid dram or in contraction also fluidram.

Contents 1 Drachm (ancient mass) 2 Dram (mass) 3 Dram (volume) 4 See also

[edit] Drachm (ancient mass)

• The Greek drachm was a weight of 1/100 Greek mine, which is about 4.37 grams.
• The Roman drachm was a weight of 1/96 Roman pounds, which is about 3.41 grams.

Greek and Roman drachm were related by the ratio 25 : 32.

The Ottoman dirhem is based on the Roman dram/drachm.

[edit] Dram (mass)

The dram is the mass of 1/256 pound avoirdupois and 1/16 ounce. So the dram weighs 875 / 32 grains.

• 7  x  64.80000 / 256  =  1.771 875 000 000 0 gram :  This is the conventional, however not the official value of the mass called dram.
• 7  x  64.79891 / 256  =  1.771 845 195 312 5 gram :  This is the legal value, about 99.998% of the value above.^{[citation needed]}

The dram (symbol: ʒ) was also the mass of 1/96 pound (℔) or 1/8 ounce (℥) in the apothecaries' system that survived until the middle of the 20th century in English-speaking countries. It was equal to 3 scruples (℈) or 60 grains (G). Thus, it was equal to 3.888 grams (in the SI).

[edit] Dram (volume)

The fluid dram is defined as 1/8 of a fluid ounce, which means it is exactly equal to

• 3.696 691 195 312 5 mL in the U.S. and
• 3.551 632 812 500 0 mL in most other Anglo-Saxon countries.

In the UK, a teaspoon was formerly defined as 1 fluid dram.

Dram is also used informally to mean a small amount of liquid, especially Scotch whisky.

[edit] See also

• Avoirdupois
• Imperial unit
• U.S. customary units
• Apothecaries' system