Sift together the flour, baking powder and salt, set aside. In a medium bowl, cream copha, butter and sugar until smooth. Stir in the egg and milk. Add dry ingredients, stir until combined, then stir in the peel and raisins. Cover and refrigerate dough until easy to handle, about 1 hour.
Preheat oven to 180 degrees C. Grease baking trays.
Place remaining 2 tablespoons of sugar into a shallow bowl or saucer. Roll dough into walnut sized balls, dip tops in the egg white then in the sugar. Place balls 5cm apart sugar side up on the prepared baking trays. Bake for 12 to 15 minutes in the preheated oven, biscuits should be golden. Cool on baking trays. These biscuits store and keep well.