Chop twenty-five clams fine and cook for half an hour in their own liquor and a cupful of boiling water in which an onion has been cooked and then strained out. Have, in another saucepan, a cupful of milk and the same of cream, with a bit of soda no larger than a pea. When it boils, stir in two large tablespoon-fuls of butter, cooked to a white roux with one of flour. Cook three minutes, take from the fire and beat in, until you have a creamy mixture, the yolks of three well-whipped eggs. Set this mixture in a pot of boiling water, and stir steadily for two minutes, then pour into the tureen. Season the chopped clams with paprica, or cayenne, salt, and minced parsley, and turn, smoking hot, upon the custard in the tureen. Serve at once before it can curdle.