http://en.wikipedia.org/wiki/Egg_cream

My mother used to first whip an egg white with a little warm chocolate; then added the milk and used a tea spoon to break the fizz of the Seltzer as it floated halfway up the glass... Then the full burst to create the head. There were times when she would use coffee in place of the chocolate. The egg white always floated to the top. There is also a coffee/egg wite/milk drink having an Italian name that children had with their breakfast, but I forget what it was called.