This section is from the book "Economical Cookery", by Marion Harris Neil. Also available from Amazon: Economical Cookery (1918).
"A dish fit for the gods."
The yolk of an egg is popularly supposed to be of a different nature from the white. But it is only oil that makes the yolk different and its proportion of yellow coloring matter. The white is merely albumen mixed with water; it contains a due proportion of saline matter which renders this natural water not at all insipid. All the potashes, sulphurs, sodas, magnesias, and acids found in the human system are in the egg-stuff, ready in proper form for due absorption when the egg, rightly cooked, is eaten. Of actual protein, there is only about fourteen per cent. in the white; the rest of it is egg-liquid, i.e., water enriched with saline matter. The yolk, identical with the white in its base, the building stuff, protein or proteid, has yet a slightly higher percentage of it, viz., fifteen per cent. In addition, it holds more sulphur and the yellow pigment so rich in tint in a good egg. The yolk depends upon its protein for its building attributes and on its oil for its warmth-making power. There is as much as thirty per cent. of this egg oil in the yolk and none in the white. The oil contains an acid as all oils do, and is the cause of the thickening of the yolk portion of the matter within the shell.
In egg cookery most people know that great heat is enduring because it coagulates the albumen, making the egg what is known as hard. Hard-cooked eggs cannot be digested save with great difficulty and disturbance. Gentle cooking is essential for eggs.
Omelets are of two kinds, according to the way they are mixed and cooked:
1. Plain omelets, sweet or savory.
2. Omelet souffles, sweet or savory.
When making omelets, have everything needed ready at hand. Chop all seasonings and flavorings fine. Break the eggs into a bowl; beat well with a fork, and stir in seasonings and one third of the butter, cut in small pieces; season with salt and pepper.
Melt a little fat in omelet or frying pan, and then, when fat is smoking hot, pour away and rub out with white paper - this prevents the omelet from sticking to the pan later. Melt rest of butter until it froths, then pour in egg mixture and stir lightly with a fork until just setting, then quickly scrape into a half-moon shape in the side of the pan, and leave for two or three seconds to set lightly. Place a hot dish against the side of the pan, and with a quick movement, invert the omelet on to it. Serve immediately.
When making omelet souffles have everything ready before commencing. Chop all seasonings and flavorings fine. Separate yolks and whites of eggs, and mix former with seasonings. Beat whites to a stiff froth and fold lightly into mixture with a metal spoon. Prepare omelet pan as above and melt butter until it froths. Pour in mixture, and cook lightly till slightly brown on under side, shaking pan and keeping edges free. Brown top, fold over quickly, and turn out on to hot dish.