CEAN the liver and remove the sinews. Put milk in a pan, add saltpetre and bring to a boil. Cool until lukewarm. Then add the liver, stir for a minute, cover and reserve for 22 hours in the refrigerator. Melt 175 g. butter in a frying pan. Remove from heat and keep in a melted state. Melt the remaining butter over low heat in a pan. Add garlic and onions and saute over medium heat until translucent. Add marjoram and white wine and bring to a boil. Lower the heat and simmer until almost dry. Remove from heat and cool to room temperature. Put port wine and madeira wine in a pan and bring to a boil. Lower the heat and simmer until reduced to one cup (60 ml.). The mousse: Beat the eggs and egg yolks together until homogenous. Remove liver from the marinade. Wash, pat dry, transfer to a blender and make a smooth puree. Remove the liver puree to a bowl. Add the onions, garlic and marjoram reduction. Mix well. Pass the mixture through a fine mesh soup strainer into a separate bowl kept over an ice bath. Then add the melted butter in a steady stream, stirring constantly. Fold in the wine reduction, the beaten eggs, cream and truffle. Sprinkle pepper and salt. Fold to mix well. Preheat the oven to 320oF. Grease four terrine moulds or ovenproof bowls or ceramic soup bowls (7.5 cm. in diameter) with a very thin layer of butter. Pour in equal quantities of the mousse, leaving 2.5 cm. from the rim. Arrange the bowls in a roasting tray. Boil enough water in a pan, pour it around the bowls in the roasting tray (it should cover half the level of the bowls). Put the tray in the preheated oven. Cover with foil and bake for two hours. Remove, cool and refrigerate. To serve: Serve as a starter with crisp melba toast.