Scruple (℈)

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

20 grains (1.296 g). A unit of the old apothecaries' system of weights.

1 scruple = 0.0012959782 kilograms (exactly).

About the scruple

Physicians and pharmacists once wrote prescriptions in Latin, and the scruple appeared in them as a small symbol followed by a Roman numeral. At 20 grains, it was the smallest of the larger apothecaries' units and amounts to roughly 1.296 grams. Three scruples made a dram, and the grain beneath it is about 64.8 milligrams.

Pharmacists in Britain were pushed away from the old scheme in the nineteenth century. The Medical Act 1858 required avoirdupois weights, and the 1864 British Pharmacopoeia advised dropping the scruple and the dram, yet the troy-based apothecaries' system lingered in practice. It became obsolete for drugs when metric measures became mandatory in 1971, and the Weights and Measures Act 1976 abolished it.

Today the unit survives mainly as a historical curiosity in old recipes and medical texts. A modern pharmacist would give the same dose as about 1.3 grams.

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

Scruple conversion chart

1 scruple expressed in every other weight & mass unit:

More Troy & apothecaries' units

• troy ounce (weight & mass)
• troy pound (weight & mass)
• pennyweight (weight & mass)
• apothecaries' dram (weight & mass)

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