The second division of the Combustible Compounds is called nitrogenous^ or flesh-forming foods. Nitrogen is the flesh-form- ing element common to all foods. It enters largely into the composition of the body, forming sixteen per cent of the animal tissue. A liberal supply is necessary to form and repair tissue. Although the atmosphere is four fifths nitro- gen, we get no supply from that source. It must be sup- plied in a state of combination, not as an element, from such compounds as have been produced under the influence of life. We require organic nitrogenous matter, and not pure nitrogen. This is sometimes derived from vegetable sources, but is most The Boston Cook Book, 461 abundant in animal substances. Animal food is richer and more nutritious than vegetable food; but the latter, if taken in large quantities, yields the same amount of flesh-forming mate- rial. Nitrogenous substances in plants and animals are identical in composition; and, from whichever source they are taken, the most important consideration is, to digest them and make them into blood. Nitrogen is an essential part of some of our most powerful medicines, like quinine and morphine, and of our most dangerous poisons, such as strychnine and prussic acid. Nitrogenous foods are also called albuminous^ because albumen is their common element, though it is called by different names in different things. Albumen is from albus, meaning white. The principal varieties of albuminous food are lean meat, fish, eggs, milk, cheese, peas, beans, oatmeal, flour, rye, and corn. These are treated more fully in other parts of the book, in chapters on Bread, Meats, Fish, Eggs, Milk, and Vegetables. The albuminous portion of meat is the juice, or albumen, and the fibre, or fibrine. In eggs it is the white. In milk it is the caseine, or the curdy part that separates when milk has soured. In peas and beans it is called vegetable caseine. In flour it is gluten, — the sticky, glutinous substance which is left after squeezing or washing out the starch. Albumen exists in two states, — one soluble in water and one insoluble. The soluble may be changed to insoluble by heating to 120°, or by adding nitric acid. It is the most easily digested of all flesh-forming foods. Albuminous substances have the property of coagulation ; but all albuminoids do not coagulate in the same way. The albumen of eggs and the juices of meat coagulate by heating to the boiling- point. The fibrine of the blood coagulates when exposed to the air. Milk coagulates by the addition of an acid. Albuminous substances also have the property of fermentation. This occurs principally in substances which are rich in sugar, starch, and gluten, like flour, milk, etc. The fermentation in flour and milk is explained in the chapter on Bread-Making. Fermentation will not take place without air or moisture, and a moderate degree of heat. Therefore, if albuminous substances be excluded from air and moisture, and kept very hot or very cold, they will not ferment. Fermentation is a change in the elements of a body composed of oxygen, carbon, and hydrogen. Sugar is composed of carbon, oxygen, and hydrogen in equal parts; when sugar ferments, it decomposes and then reunites in 462 The Boston Cook Book. different proportions, forming different compounds, — alcohol, carbonic acid, and water.

AI-modernized reading of the original text

The second division of the Combustible Compounds is called nitrogenous, or flesh-forming foods. Nitrogen is the flesh-forming element common to all foods. It enters largely into the composition of the body, forming sixteen per cent of the animal tissue. A liberal supply is necessary to form and repair tissue. Although the atmosphere is four fifths nitrogen, we get no supply from that source. It must be supplied in a state of combination, not as an element, from such compounds as have been produced under the influence of life. We require organic nitrogenous matter, and not pure nitrogen. This is sometimes derived from vegetable sources, but is most The Boston Cook Book, 461 abundant in animal substances. Animal food is richer and more nutritious than vegetable food; but the latter, if taken in large quantities, yields the same amount of flesh-forming material. Nitrogenous substances in plants and animals are identical in composition; and, from whichever source they are taken, the most important consideration is, to digest them and make them into blood. Nitrogen is an essential part of some of our most powerful medicines, like quinine and morphine, and of our most dangerous poisons, such as strychnine and prussic acid. Nitrogenous foods are also called albuminous, because albumen is their common element, though it is called by different names in different things. Albumen is from albus, meaning white. The principal varieties of albuminous food are lean meat, fish, eggs, milk, cheese, peas, beans, oatmeal, flour, rye, and corn. These are treated more fully in other parts of the book, in chapters on Bread, Meats, Fish, Eggs, Milk, and Vegetables. The albuminous portion of meat is the juice, or albumen, and the fibre, or fibrine. In eggs it is the white. In milk it is the caseine, or the curdy part that separates when milk has soured. In peas and beans it is called vegetable caseine. In flour it is gluten, — the sticky, glutinous substance which is left after squeezing or washing out the starch. Albumen exists in two states, — one soluble in water and one insoluble. The soluble may be changed to insoluble by heating to 120°, or by adding nitric acid. It is the most easily digested of all flesh-forming foods. Albuminous substances have the property of coagulation ; but all albuminoids do not coagulate in the same way. The albumen of eggs and the juices of meat coagulate by heating to the boilingpoint. The fibrine of the blood coagulates when exposed to the air. Milk coagulates by the addition of an acid. Albuminous substances also have the property of fermentation. This occurs principally in substances which are rich in sugar, starch, and gluten, like flour, milk, etc. The fermentation in flour and milk is explained in the chapter on Bread-Making. Fermentation will not take place without air or moisture, and a moderate degree of heat. Therefore, if albuminous substances be excluded from air and moisture, and kept very hot or very cold, they will not ferment. Fermentation is a change in the elements of a body composed of oxygen, carbon, and hydrogen. Sugar is composed of carbon, oxygen, and hydrogen in equal parts; when sugar ferments, it decomposes and then reunites in The Boston Cook Book. different proportions, forming different compounds, — alcohol, carbonic acid, and water.

Mrs. Lincoln's Boston cook book