Beat egg yolks lightly, add cold water and beat thoroughly.
Beat in hot water and pinch of salt.
Add sugar, cake flour and baking powder, beating well after each addition.
In seperate bowl beat egg whites and cream of tartar untill stiff peaks form.
Add vanilla and beat well.
Fold into egg yolk mixture
Pour into ungreased 10-inch tube pan.
Run knife through batter to remove trapped air bubbles.
Bake at 325 degrees for 1 hour.
Invert cake to cool and remove from pan.