Albumins
Aiton's Encyclopedia (1910)
al-bu mins, a class of nitrogenous substances occurring naturally in animals and plants. The white of an egg is a nearly pure, concentrated solution of albumin (egg-albumin) in water. Albumins constitute an important ingredient of the blood of animals, and also of milk. Wheat, oats, rye, and nearly all vegetables yield some albumin. In many vegetables the albumin is lost when the material is soaked in cold water for some length of time. Animal and vegetable albumins do not differ much from one another in composition, and are composed of carbon, oxygen, nitrogen, hydrogen, and sulphur. Albumins are soluble in water and coagulated by heat. When added to certain liquors, they have the property of combining with some of the suspended solid matters and carrying them to the bottom. On account of this property, white of an egg is used frequently to clear coffee. Blood albumin was at one time extensively used in sugar refineries to clear sugar. In cases of poisoning, especially from corrosive sublimate, the white of an egg is sometimes a successful remedy, since in coagulating it combines with the poisonous substance and serves to prevent its action on the stomach. Albumins constitute an important ingredient in animal and human food. An animal can exist for a considerable time without fats and carbohydrates, but its death is assured by the withdrawal of albumins from its nourishment. Commercial albumin is obtained chiefly from two sources, eggs and the serum of blood. It the arts it is used to size paper or give it a lustrous coating, and to secure fast colors in connection with dyeing and printing. It is also used in photography and pharmacy, and in the manufacture of confectionery. Slaked lime forms with albumin solution a useful cement. The term "albumen," was originally a name applied by scientists to the white of an egg. It is derived from a Latin word albus, signifying white. In botany the word has been extended to apply to that portion of a seed technically known as the endosperm, although the seed may or may not be rich in albumins. Seed albumen is best illustrated in the hemispherical halves of beans, peas, coffee, and peanuts--the nourishment stored up in the seed. It also constitutes the floury part in corn, wheat, and like grains, the oily part in poppy seeds, and the fleshy part in the cocoanut.
What Has Changed in the Last Century
Aiton's 1910 account has the chemistry right in outline — carbon, oxygen, nitrogen, hydrogen and sulphur, soluble in water, coagulated by heat — but it had no way to say what an albumin actually is. Albumins are proteins, long chains of amino acids folded into a definite shape: human serum albumin is now known to be a single chain of 585 residues, and Edwin Cohn's Harvard team worked out how to fractionate it from plasma in 1940, so that dried and liquid albumin was carried as a shock and burn treatment through the Second World War and is a standard hospital product today. The claim that an animal dies if albumins are withdrawn from its food proved essentially correct, and was refined into the modern list of essential amino acids the body cannot make for itself. The industrial uses have mostly gone — blood albumin no longer clears sugar — and the old first-aid trick of egg white for corrosive sublimate poisoning has been dropped from medical practice.
Written for this edition, 2026.