Break the eggs, yolks and whites separately, and beat the yolks to a creamy froth. Beat the whites till they can be turned upside down without spilling. Put yolks and whites together, and beat till blended; then add the sugar slowly; then the lemon rind and juice and the salt, and last the flour. Whisk together as lightly and quickly as possible. Turn into either three buttered bread-pans, or bake in a large loaf, as preferred. Fill the pans two-thirds full, and, when in the oven, do not open it for ten minutes. Bake about half an hour, and test by running a clean broom-straw into the loaf. If it comes out dry, they are done. Turn out, and cool on a sieve, or on the pans turned upside down.