Mrs. S.T. Rorer, Many Ways for Cooking Eggs — Cooking of Eggs (1907)
“ The white of eggs, almost pure albumin, is nutritious, and, when cooked in water at 170 degrees Fahrenheit, requires less time for perfect digestion than a raw egg. The white of a hard-boiled egg is tough and quite insoluble. The yolk, however, if the boiling has been done carefully for twenty minutes, is mealy and easily digested. Fried eggs, no matter what fat is used, are hard, tough and insoluble. ”
