The minim (abbreviated min) is a unit of volume in both the imperial and U.S. customary systems of measurement. Specifically, in the imperial system, it is of an imperial fluid drachm or of an imperial fluid ounce; in the U.S. customary system, it is of a US customary fluid dram or of a US customary fluid ounce. <!--Commented-out text, assertion: "In the Pharmacopoeia, it is also noted that the minim was originally created by Mr Timothy Lane, F.R.S., as parts per wine gallon."--><!--Questions: "the" Pharmacopoeia? Which one? You mean the British Pharmacopoeia? If so, then which edition thereof? Feel free to put this sentence back into the article IF a real reference citation is entered. I spent some time trying to verify the assertion using Google Books search, without the £875.00 it takes to get past the paywall of the current edition of the British Pharmacopoeia, but without success. I searched inside various 19th-century editions and Latin-to-English translations of The Pharmacopœia of the Royal College of Physicians of London but the search claimed to find no "Lane". Example editions: https://www.google.com/books/edition/The_Pharmacopœia_of_the_Royal_College_o/26hdAAAAcAAJ (1809) and https://www.google.com/books/edition/Translation_of_the_Pharmacopœia_of_the/wd9ZAAAAcAAJ (1851) -->
The minim was introduced in the 1809 edition of The Pharmacopœia of the Royal College of Physicians of London as a replacement for the drop, which had previously been the smallest unit of the apothecaries' system. It was observed that the size of a drop can vary considerably depending upon the viscosity and specific 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", later known as the minim-tube. The minim-tube was a type of graduated pipette, a device invented in 1791 by François-Antoine-Henri Descroizilles.
Apothecaries' measures are fully defined in the United Kingdom's Weights and Measures Act 1878, but the UK's Weights 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 the metric system, and even in the least metricated countries, pharmacy is largely metricated and the apothecaries' system is deprecated. The unit may rarely persist in some countries in the measurement of dosages of medicine.
Definitions
{| class="wikitable"
! Imperial minim
! US customary minim
|-
| imperial fluid ounce
| US fluid ounce
|-
| UK teaspoon
| US teaspoon
|-
| imperial fluid drachm
| US fluid dram
|-
|59.193880208 microlitres (exactly)
| microlitres (exactly)
|-
|≃ 0.0036122322 cubic inches
| cubic inch (exactly)
|-
|≃ 0.002001583 US fluid ounces
|≃ 0.002168422 imperial fluid ounces
|-
|≈ 0.96076 US fluid minims
|≈ 1.0408427 imperial minims
|}