Moist Chocolate Cake

Cream butter, sugar and eggs. Add flour, salt, vanilla and cocoa - mix and add the sour milk which the 2 teaspoons of soda have been added to - mix until blended. Then slow, add the boiling water, the batter will be very thin. Bake in a 9 x 13 inch or two 9 inch round pans for 30 minutes at 375 degrees. Freezes well and stays moist for days.