It's a Chinese cash coin, of the Ch'ien Lung emperor (spelled "Qian Long" in the modern Chinese fashion), who ruled 1736-1795. The coins are undated, but ought to have a mintmark on the other side. 24 mintmarks are recorded for this emperor.
Here's a link showing some of these coins.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis