Gold extraction the purity of gold. The parting of gold from silver has been done since ancient times starting in Lydia in the 6th century BC. Various techniques have been practised; salt cementation from ancient times, parting using distilled mineral acids from medieval times, and in modern times using chlorination using the Miller process and electrolysis using the Wohlwill process. Gold extraction Gold extraction refers to the processes required to extract gold from its ores. This may require a combination of comminution, mineral processing, hydrometallurgical, and pyrometallurgical processes to be performed on the ore. Gold mining from alluvium ores was once achieved
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