1. To clarify stock, first strain it; then separate an egg (discard the yolk or save for another use). In a small bowl combine the egg white and 1/4 cup cold water.
2. Stir the mixture into the hot, strained stock. Bring to boiling. Remove from heat and let stand for 5 minutes. (As the egg white cooks, it will coagulate and trap fine particles from the stock.)
3. Place a large sieve or colander lined with several layers of damp 100-percent cotton cheesecloth over a large bowl. Pour the stock through the cloth to strain out the particles and egg white.