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 is a great metal to scrap, and is always worth more then brass, but less then copper. Bronze generally consists of 90 percent copper and 10 percent zinc. There are multiple other types of metals that may look like bronze, but unless you have it completely clean, it will be a hard item to sell as bronze.