Comparison of the imperial and US customary measurement systems metre, as 1852 metres. Traditionally, both Britain and the US used three different weight systems: troy weight for precious metals, avoirdupois weight for most other purposes and apothecaries' weight for medicines. However, apothecaries' weight has now been superseded by the metric system. One important difference is the widespread use in Britain of the stone of 14 pounds () for body weight. This unit is not used in the United States, although its influence was seen in the practice, until World War II, of selling flour by a barrel of 196 pounds (14 stone). Another difference arose when Britain abolished the
Metals in medicine have been used in treatments since ancient times. The Ebers Papyrus from 1500BC is the first written account of the use of metals for treatment and describes the use of Copper to reduce inflammation and the use of iron to treat anemia. Sodium vanadate has been used since the early 20th century to treat rheumatoid arthritis. Recently metals have been used to treat cancer, by specifically attacking cancer cells and interacting directly with DNA. The positive charge on most metals can interact with the negative charge of the phosphate backbone of DNA. Some drugs developed that include metals interact directly