Theminim (abbreviatedmin) is aunit ofvolume in both theimperial andU.S. customary systems of measurement. Specifically, in the imperial system, it is1⁄60 of animperial fluid drachm[1][2] or1⁄480 of animperial fluid ounce; in the U.S. customary system, it is1⁄60 of aUS customary fluid dram or1⁄480 of aUS customary fluid ounce.[3][4]
The minim was introduced in the 1809 edition ofThe Pharmacopœia of the Royal College of Physicians of London as a replacement for thedrop, which had previously been the smallest unit of theapothecaries' system.[5] It was observed that the size of a drop can vary considerably depending upon theviscosity andspecific gravity of the liquid. (At the time, the phenomenon of surface tension was not well understood.) The minim, on the other hand, was measured with a graduated glass tube known as a "minimometer",[6] later known as the minim-tube.[7] The minim-tube was a type of graduatedpipette, a device invented in 1791 byFrançois-Antoine-Henri Descroizilles.
Apothecaries' measures are fully defined in the United Kingdom'sWeights and Measures Act 1878, but the UK'sWeights and Measures Act 1963 provided for the abolition of the minim,fluid scruple, and fluid drachm, all already obsolete. Actual delegalization occurred on 1 February 1971.
The use of the minim, along with other such measures, has been reduced by the adoption of themetric system, and even in the leastmetricated countries, pharmacy is largely metricated and theapothecaries' system is deprecated. The unit may rarely persist in some countries in the measurement of dosages of medicine.
| Imperial minim | US customary minim |
|---|---|
| 1/480 imperial fluid ounce | 1/480 US fluid ounce |
| 1/60 UK teaspoon | 1/80 US teaspoon |
| 1/60 imperial fluid drachm | 1/60 US fluid dram |
| 59.1938802083 microlitres (exactly) | 61.611519921875 microlitres (exactly) |
| ≃ 0.0036122322 cubic inches[8] | 77/20480 cubic inch (exactly)[9] |
| ≃ 0.002001583 US fluid ounces | ≃ 0.002168422 imperial fluid ounces |
| ≈ 0.96076 US fluid minims | ≈ 1.0408427 imperial minims |