This section is from the book "The American Woman's Cook Book", by Ruth Berolzheimer. Also available from Amazon: The Domestic Arts Edition of the American Woman's Cook Book.
Cream the Butter or Other Shortening by continued rubbing against the sides of the bowl until it is soft and light. Some people prefer to use a wooden spoon for this, but a fork does the work more quickly. If the shortening is too hard to cream easily, warm the bowl slightly by setting it in warm water, but do not melt the fat.
Add the Sugar Gradually and work well after each addition.
Separate the Whites From the Yolks of the eggs. Beat the yolks until they are thick and lemon-colored, then add them to the creamed shortening and sugar. If the egg is not separated, beat the whole egg well and add here.
Add the Dry Ingredients and Milk to the first mixture, alternately, keeping the batter of the same consistency throughout the mixing process. Beat just enough to make the mixture smooth.
Add the Flavoring, then fold in the stiffly beaten egg-whites, unless the whites were added with the yolks.
Melt Chocolate Over Hot Water and add just after the egg-yolks. Add cocoa as one of the dry ingredients.