ALBUMEN is an organic compound, found both in animal and vegetable substances. It forms the chief ingredient in the white of egg, and abounds in the blood and chyle, and more or less in all the serous fluids of the animal body: it also exists in the sap of vegetables, and in their seeds and other edible parts. A. forms the starting point of animal tissues, for in an egg during incubation all the parts of the chick are formed out of it. The organized substances, fibrine and caseine, have a chemical composition similar to A. • and hence, along with A., they are called albuminous compounds. A. may be considered a raw material of fibrine, and fibrine as animalized A.
The chief component elements of A. are carbon, hydrogen, nitrogen, and oxygen, with small proportions of phosphorus and sulphur. It is believed to be a definite chemical com pound, though the exact proportions and the rational formula have not been definitely ascertained. Carbon forms about 54 per cent of it; nitrogen, 16; and sulphur, 2. It is the sulphur of the A. that blackens silver when brought in contact with eggs, and the smell of rotten eggs arises from the formation of suiphureted hydrogen during the decomposition.
A. is soluble in water, and in such a state of solution is found in the egg, the juice of flesh, the serum of blood, and the, juke- of vegetables; but when heated from 140° to 160° it coagulates, and is no longer soluble in water. With bichloride of mercury (corrosive
sublimate), sulphate of copper (blue vitriol), acetate of lead (sugar of lead), nitrate of silver (lunar caustic), it forms insoluble compounds, and is therefore used as an antidote to these poisons. The property of coagulating with heat adapts A. for the purpose of clarifying in sugar-refining and other processes. The A. is added to the liquid in the cold state, allowed to mix thoroughly therein, and then, when heated, it coagulates, entangling and separating all the impurities suspended in the liquid. A. is likewise coagulated by the majority of the mineral acids, but not by acetic acid. Alcohol, ether, creosote, and tannic acid likewise cause the coagulation of A., and hence the efficacy of these substances, especially the two latter, in coagulating and thereby killing the nerves which cause so much pain in toothache. The importance of A. as an article of diet will be discussed under FOOD.