Chocolate Cake without eggs

1 cup sugar
1/4 cup butter, melted
1/4 cup thick sour milk
1 tsp. vanilla
2 Tbsp. cocoa
1/2 cup water, boiling
1 tsp. soda
2 cups pastry flour

Cream 1 cup sugar, 1/4 cup melted butter together; add 1/4 cup thick sour milk, 1 tsp. vanilla, 2 Tbsp. cocoa dissolved in 1/2 cup boiling water, 1 tsp. soda sifted with 2 scant cups pastry flour. Mix all ingredients well and bake in a moderate oven until done.