傷寒論中之「兩」如何換算為現今之「克」

How to Converse the Weight Unit of Liang in “Shang Han Lun” to Gram

長久以來，對於《傷寒論》藥物重量的古今折算一直存在著爭議，目前在用藥劑量的古今轉換上基本有四種，包括一兩等於15.6克、3.75克、1.3克與13.75克。現今多數臨床中醫師開立藥物劑量，多參照明代醫家李時珍在《本草綱目》提出的「今古異制，古之一兩，今用一錢，可也」以及汪昂《湯頭歌訣》:「大約古用一兩，今用一錢足矣」的換算方式，即為一兩等於3.75克。然而，在同一方劑的組成藥材中，若有以非重量度量的藥物時，例如用體積為單位量秤藥物，即出現與重量度量藥材之間的不合理落差。本研究比較以重量計量與非重量計量的藥材間之實物份量，以及比較煎煮時所需水量與總藥材量之間的相對份量，藉由這些方式，檢視那一種重量的折合計算方式較符合《傷寒論》原方劑量的精神，結果顯示一兩應等於13.75克。

The issue about the weight conversion in terms of prescription in Chinese Medicine from Liang (兩) used in Shang Han Lun (傷寒論), written in Han (漢) dynasty, into the unit, Grams, has beencontroversial for a long time. Four different perspectives exist among the Chinese medicine practitioners: 1 liang is equal to 15.6 grams, 3.75 grams, 1.3 grams, and 13.75 grams, respectively. Yet, nowadays, most Chinese Medicine practitioners prescribe followed a saying that “1 liang is equal to 1 qian (錢),” where 1 qian is considered to be 3.75 grams, from both Li Shizhen (李時珍), the author of Compendium of Materia Medica (本草綱目), and Wang Ang (汪昂), the complier of Tangtou Gejue (湯頭歌訣), yet both reflect the weight unit used in Ming (明) dynasty rather than in Han (漢) dynasty.
Meanwhile, in a Chinese medicine formula, there are several herbs measured in different unit such as weight, numbers, and volume. In a formula with different measurement, there will be a dramatic difference applying all herbs into a weight unit based on an equation that “1 liang is equal to 1 qian”. There is apparently a significant gap between the amount of medicine used in Shang Han Lun and the amount most Chinese medicine practitioners applied nowadays due to the discrepancy of the weight units. This study attempted to use a practical way to approach the historical problem, and reached the conclusion that 1 liang described in Shang Han Lun should be equal to 13.75 grams.