In bowl, sift together flour, 1 cup sugar, salt and baking powder.

In another bowl, combine egg whites and cream of tartar.

Beat until think.

Slowly add 1/2 cup sugar and beat until mixture is stiff.

In a third bowl combine egg yolks, water, vanilla, lemon juice and grated rind.

Add this to the dry mixture and beat for 1 minute.

Slowly fold in egg white, blending well.

Pour into ungreased 10 inch tube pan.

Bake for 40- 45 minutes at 350.

Invert pan and cool for 1 hour before removing cake from pan.