Preheat the oven to 350 degrees. Grease and flour two, 8-inch round layer cake pan or a 13x9-inch oblong pan.
Mix the sugar, flour, cocoa and the salt. Add the sour cream, melted butter and the eggs; beat until it’s smooth. Add the baking soda which has been dissolved in the boiling water; mix well.
Pour into the prepared pan and bake for about 30 minutes or until a cake tester or toothpick inserted in the middle of the cake comes out clean. Cool for 10 minutes on wire racks and then turn out onto the racks and finish cooling completely. Frost as desired.
Source: Favorite Recipes from Progressive Farmer, 1967