Preheat oven to 350º. Grease and lightly flour a 10” tube pan.
Cream butter in a medium bowl with electric mixer gradually adding sugar. Continue beating until the mixture is soft and light. Add the lime rind with the eggs, on at a time, beating a teaspoon of flour with the addition of each egg. Sift the remaining flour, salt and the baking soda onto waxed paper, Stir the flour mixture into the cake, adding the lime juice and the vanilla. Mix well to incorporate.
Pour the mixture into the prepared pan and smooth the top. Bake for 1-1/4 hour or until pick comes out clean. Let cake cool in pan, after transferring to serving dish, dust if desired with confectioners sugar.