Convert from ounce to dram [apothecaries]

Unit Definition (ounce)
The ounce is a traditional unit of weight. The avoirdupois ounce, the unit commonly used in the United States, is 1/16 pound or about 28.3495 grams. The avoirdupois ounce also equals 175/192 = about 0.911 457 troy ounce or 437.5 grains. The word ounce is from the Latin uncia, meaning a 1/12 part, because the Roman pound was divided into 12 ounces. The word "inch," meaning 1/12 foot, has the same root.

Unit Definition (dram [apothecaries])
The dram [apothecaries] is a unit of weight in the traditional system of English apothecaries, equal to 60 grains, 3 scruples, 1/8 troy ounce, or approximately 3.8879 gram. See troy weights for additional information. The apothecaries' dram is sometimes abbreviated dr. ap. to distinguish it from the avoirdupois dram. It is equivalent to about 2.1943 avoirdupois drams. There is a similar Italian unit, the dramma, equal to 72 grani or roughly 3.5 grams.