Gold costs were about $317 per troy ounce in 2007, but these can vary widely depending on mining type and ore quality; global mine production amounted to 2,471.1 tonnes. After initial production, gold is often subsequently refined industrially by the Wohlwill process which is based on electrolysis or by the Miller process, that is chlorination in the melt. The Wohlwill process results in higher purity, but is more complex and is only applied in small-scale installations. Other methods of assaying and purifying smaller amounts of gold include parting and inquartation as well as cupellation, or refining methods based on the dissolution
Purity and Danger Purity and Danger Purity and Danger: An Analysis of Concepts of Pollution and Taboo is a 1966 book by the anthropologist and cultural theorist Mary Douglas. It is her best known work. In 1991 the "Times Literary Supplement" listed it as one of the hundred most influential non-fiction books published since 1945. It has gone through numerous reprints and re-editions (1969, 1970, 1978, 1984, 1991, 2002). In 2003 a further edition was brought out as volume 2 in "Mary Douglas: Collected Works" (). The line of inquiry in "Purity and Danger" traces the words and meaning of dirt in different