I had read that the Japanese 1-yen, an aluminum coin, would float if it was placed in water gently enough. (Water’s surface tension.) I wanted to test the idea, so I found a 1973 (Showa 48) Japanese 1-yen and gently placed it in a bowl of water. Sure enough—it floated. So I tried several other aluminum coins, very much at random. A 1955 Italian 5-lire floated. So did a 2006 Chinese 1-fen.
A few evenings later when I saw this envelope, and thought of the island of Reunion, alone in the middle of the ocean, I knew I had to see whether this coin—the 1964 Reunion 1-franc—would float too....
