Convert from ounce [troy] to dram [apothecaries]

Unit Definition (ounce [troy])
The ounce [troy] is a second traditional unit of mass or weight. The troy ounce, traditionally used in pharmacy and jewelry, is 1/12 troy pound, 480 grains, or about 31.1035 grams. Thus the troy ounce equals 192/175 = 1.09714 avoirdupois ounces. This unit is the traditional measure for gold and other precious metals; in particular, the prices of gold and silver quoted in financial markets are the prices per troy ounce. The troy ounce is divided into 20 pennyweight or into 8 troy drams.

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.