Fats and oils contain three different oleaginous substances, known as stearine, margarine, and oleine. Oleine is that portion of oil that causes its fluidity. It is more abundant in oils than fats, and in the fat of swine than in the harder fat of sheep or beef. Lard is better than mutton fat or suet for frying, because, having more oleine, it can be converted into a liquid sooner. Margarine is harder than oleine. It exists in human fat, in but- ter, and olive oil. Stearine is the most solid substance of the three, and is most abundant in tallow and suet. The peculiar odor some fats and oils possess is from the pres- ence of an acid. In butter it is butyric acid. Glycerine is the base common to all the fats. In stearine, the hardest fat, it unites with stearic acid; in margarine, a less solid form, with margaric acid; in oleine, or oil, with oleic acid. Fat forms the chief material of adipose tissue. It serves to fill spaces and give rotundity and beauty to the form, to equalize external pressure, to diminish the friction of the parts, to give suppleness to the tissues, and, being a non-conductor of heat, to keep the body warm. An undue accumulation of fat is a species of disease." Oils and fats will not mix with water; but if an alkaline sub- stance, like potash or soda, be added, the oil becomes separated into fine particles, and is held suspended in the watery fluid. This is called an emulsion, and this is what takes place in intes- tinal digestion. The gastric juice, being acid, does not digest fat, but only separates it from these substances, that it may digest the albuminous portions with which it is mingled. But 460 The Boston Cook Book. the pancreatic fluid, being alkaline, resolves the fat into an emulsion. This completes the digestion, then the fats are ab- sorbed and received into the general circulation. Having a strong affinity for oxygen, these fatty particles in the venous blood, when they come in contact with the oxygen of the air, burn, and heat is evolved. The power of fat in maintaining heat and activity is two and a half times that of starch. Oils which are used as food are fixed oils. Volatile oils are found in many condiments and perfumes. Volatile oils can be distilled, or changed to vapor, and recondensed into their origi- nal form; they leave no permanent stain on paper. Fixed or greasy oils cannot be distilled; before changing to vapor they recombine into new compounds. Gum, Mucilage, Pectose, and Cellulose. These are combustible compounds, but are neither starchy, saccharine, nor oily. Gum is found in apple and plum trees. Gum arable is from a species of acacia, and is soluble. Muci- lage is found in onions, quinces, and flaxseed. It forms a jelly with water, but does not dissolve like gum arable. Pectose is found in many roots, like the turnip; also in the pear and peach. When boiled with water it changes to a vegetable jelly, called pectine. Currants, pears, peaches, plums, contain pectine, and this is what gives firmness to the preserves made from them. Cellulose is the woody fibre of stalks of grain, the membrane which envelops the grains, husks, and skin of seeds, rinds, cores, and stones of fruits. It is the main and almost the sole constituent of linen, and of the paper which is made from linen. NITROGENOUS FOODS.

AI-modernized reading of the original text

Fats and oils contain three different oleaginous substances, known as stearine, margarine, and oleine. Oleine is that portion of oil that causes its fluidity. It is more abundant in oils than fats, and in the fat of swine than in the harder fat of sheep or beef. Lard is better than mutton fat or suet for frying, because, having more oleine, it can be converted into a liquid sooner. Margarine is harder than oleine. It exists in human fat, in butter, and olive oil. Stearine is the most solid substance of the three, and is most abundant in tallow and suet. The peculiar odor some fats and oils possess is from the presence of an acid. In butter it is butyric acid. Glycerine is the base common to all the fats. In stearine, the hardest fat, it unites with stearic acid; in margarine, a less solid form, with margaric acid; in oleine, or oil, with oleic acid. Fat forms the chief material of adipose tissue. It serves to fill spaces and give rotundity and beauty to the form, to equalize external pressure, to diminish the friction of the parts, to give suppleness to the tissues, and, being a non-conductor of heat, to keep the body warm. An undue accumulation of fat is a species of disease." Oils and fats will not mix with water; but if an alkaline substance, like potash or soda, be added, the oil becomes separated into fine particles, and is held suspended in the watery fluid. This is called an emulsion, and this is what takes place in intestinal digestion. The gastric juice, being acid, does not digest fat, but only separates it from these substances, that it may digest the albuminous portions with which it is mingled. But The Boston Cook Book. the pancreatic fluid, being alkaline, resolves the fat into an emulsion. This completes the digestion, then the fats are absorbed and received into the general circulation. Having a strong affinity for oxygen, these fatty particles in the venous blood, when they come in contact with the oxygen of the air, burn, and heat is evolved. The power of fat in maintaining heat and activity is two and a half times that of starch. Oils which are used as food are fixed oils. Volatile oils are found in many condiments and perfumes. Volatile oils can be distilled, or changed to vapor, and recondensed into their original form; they leave no permanent stain on paper. Fixed or greasy oils cannot be distilled; before changing to vapor they recombine into new compounds. Gum, Mucilage, Pectose, and Cellulose. These are combustible compounds, but are neither starchy, saccharine, nor oily. Gum is found in apple and plum trees. Gum arable is from a species of acacia, and is soluble. Mucilage is found in onions, quinces, and flaxseed. It forms a jelly with water, but does not dissolve like gum arable. Pectose is found in many roots, like the turnip; also in the pear and peach. When boiled with water it changes to a vegetable jelly, called pectine. Currants, pears, peaches, plums, contain pectine, and this is what gives firmness to the preserves made from them. Cellulose is the woody fibre of stalks of grain, the membrane which envelops the grains, husks, and skin of seeds, rinds, cores, and stones of fruits. It is the main and almost the sole constituent of linen, and of the paper which is made from linen. NITROGENOUS FOODS.

Mrs. Lincoln's Boston cook book