Dram (unit)

For the related unit of currency, see Greek drachma.

The dram (alternative British spelling drachm; apothecary symbol ʒ or ℨ; abbreviated dr) was originally both a coin and a weight in ancient Greece. It refers to a unit of mass in the avoirdupois system, and both a unit of mass and a unit of volume in the apothecaries' system. The unit of volume is more correctly called a fluid dram, fluid drachm, fluidram or fluidrachm (abbreviated fl dr, ƒ 3, or fʒ).

Ancient unit of mass

• The Attic Greek drachma was a weight of 6 obols, ​¹⁄₁₀₀ Greek mina, or about 4.37 grams.
• The Roman drachma was a weight of ​¹⁄₉₆ Roman pounds, or about 3.41 grams.

The Ottoman dirhem was based on the Sassanian drachm, which was itself based on the Roman dram/drachm.

Modern unit of mass

In the avoirdupois system, the dram is the mass of ​¹⁄₂₅₆ pound or ​¹⁄₁₆ ounce. The dram weighs ​⁸⁷⁵⁄₃₂ grains, or exactly 1.7718451953125 grams.

In the apothecaries' system, which was widely used in the United States until the middle of the 20th century, the dram is the mass of ​¹⁄₉₆ pounds apothecaries (lb ap), or ​¹⁄₈ ounces apothecaries (oz ap or ℥) (the pound apothecaries and ounce apothecaries are equal to the troy pound (lb t), and troy ounce (oz t), respectively). The dram apothecaries is equal to 3 scruples (s ap or ℈) or 60 grains (gr), or exactly 3.8879346 grams.

"Dram" is also used as a measure of the powder charge in a shotgun shell, representing the equivalent of black powder in drams avoirdupois.

Unit of volume

A 'wee dram' being added to flavour the haggis at a Burns Supper

The fluid dram is defined as ​¹⁄₈ of a fluid ounce, and is exactly equal to:

• 3.6966911953125 ml in US customary units [3785.411784 ÷ 1024]
• 3.5516328125 ml in British Imperial units [4546.09 ÷ (160 × 8)]

A teaspoonful has been considered equal to one fluid dram for medical prescriptions. However, by 1876 the teaspoon had grown considerably larger than it was previously, measuring 80–85 minims. As there are 60 minims in a fluid dram, using this equivalent for the dosage of medicine was no longer suitable. Today's teaspoon is equivalent to approximately ​1 ¹⁄₃ US fluid drams, or 80 US minims.

Dram is used informally to mean a small amount of spirituous liquor, especially Scotch whisky. The unit is referenced by the phrase dram shop, the U.S. legal term for an establishment that serves alcoholic beverages.

In popular culture

The line "Where'd you get your whiskey, where'd you get your dram?" appears in some versions of the traditional pre-Civil War American song "Cindy." In Monty Python's song entitled The Bruces' Philosophers Song there is the following line: "Hobbes was fond of his dram". In the old-time music tradition of the United States, there is a tune entitled "Give the Fiddler a Dram".

External links

• Appendix C – General Tables of Units of Measurement in Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices. NIST Handbook 44 (2012 ed.).
• Image of Ancient Greek silver drachm with flying Pegasus, Acarnania, Leucas, c. 470–450 BCE