The CPI takes a constant basket of goods and sees how the price changes from year to year. If the price of the basket of goods increases, then there is price inflation. If the price of the basket of goods decreases, then there is deflation.
Copper and tin mainly make up bronze but other elements include phosphorus, manganese, silicon and aluminium.
Bronze, the first alloy created by people, is a mix of copper that contains as much as 25% tin. Early people used bronze to make tools, weaponry, containers and ornamental items.