Classroom Activity for the NOVA program Newton's Dark Secrets: In Secret Symbols, students read and interpret a passage from a famous alchemical text titled The Twelve Keys of Basil Valentine ...

Identifiable silver stockpiles are thought to be roughly 650 million ounces. 150,000 tons of gold and 650 million or so ounces of silver sound like a lot, but one must consider that a good deal of ...