So you are saying you bought one silver and then revealed trader MANY times on the same turn to empty the silver pile? Unfortunately you can't do that - from the rule book: "Trader is also a reaction. When you gain a card, whether due to buying it or due to gaining it some other way, you may reveal Trader from your hand to instead gain a silver from the supply. If you do this, you gain a silver, not the card you would have gained." So I would say in this case you would gain the silver, reveal Trader, and instead of gaining a silver, you would gain the same silver. Not gain an additional silver and then multiple subsequent silvers.