Start with bowl #1 and beat the butter with the sugar until light, then add the eggs, one at a time, and beat in until light.

Now go to bowl #2 and stir the baking soda into the sour cream.

Now go to bowl #3. mix together the flour,salt,and cocoa.

Add the flour mixture alternatively with the sour cream mixture to the butter mixture, but do not beat too much. Take off the beater and add the boiling water and carefully stir it inches Pour the batter in a greased 9 x 13 inch baking pan or two greased layer cake pans and bake in a preheated 350 F oven for about 30 minutes, or until done (test with toothpick). Ice with desired chocolate frosting.