12 eggs, separated
6 cups sugar
3 cups shortening
2 tablespoons vanilla extract
1 teaspoon salt
9 cups flour, plus additional for flouring blueberries and cake pan
2 tablespoons baking powder
2 cups milk
6 cups blueberries
Butter, for greasing pan
Beat the egg whites; set aside. Mix the egg yolks with sugar, shortening, vanilla, and salt.
In a separate bowl mix the 9 cups of flour and the baking powder. Mix the flour mixture with the egg mixture, slowly adding the milk. Fold in the egg whites.
Flour the blueberries and then fold them into the cake batter.
Butter and flour 2 (12 by 18 by 1-inch) baking pan. Pour the blueberry cake batter into the pans and bake for 40 minutes, or until a toothpick inserted into the cake comes out dry and the cake springs back when touched firmly.