Glue is common in impure gelatine obtained from animal substance, especially from parings of ox or other thick hides, ears of oxen and sheep, skins of rabbits, hares, cats and dogs, parings of leather, parchment, old gloves, etc. It is steeped with lime- water to remove blood and fatty parts, and is then . dried and stored. After washing, it is put into vats in an open boiler with water, and thus the gluey parts are dissolved from the leather. Samples are taken and tested in water to see if they are clean. If heated at or above boiling-point too long it loses the power of congealing. Boiling separates the impurities; after the glue has solidified it is sliced and dried for several 184 DOMESTIC SCIENCE days. It is transparent and has glassy fracture. It is used as cement for joining wood, etc. When any connective tissue, including bone-car- tilage and gristle, is boiled for a long time, a solution is obtained which when cooked forms a jelly. Half of the solid parts of the animal are convertible into gelatine by boihng with water. Calves' feet produce gelatine on comparatively httle boihng, older parts on more boiling. Parts of an old animal are not so soluble as of the young. From the several connective tissues various gelatines are then obtained. From ordinary connective tissues we get collagen, from bones ossein, from cartilage choudrin, from super- ficial tissues (skin, nails, etc.) kreatin; all are forms of gelatine. The species of gelatine fibroin is ob- tained by boiling spiders' webs, silk of silk-worm, etc. Both tissues are hquid in the animal and solidify on exposure. Fibroin is also found in fibres of sponges. Chutin is the basis of bodily structiu-e in insects. It forms the skeleton of crabs and lobsters and is not so soluble as gelatine of meats. Preparation of Gelatine. The parts are cleaned, cut small, and then boiled with water for some time. At- tention is paid to the purity of the product. It is sometimes purified with charcoal or with ox's blood. The albumen of blood coagulates, rises as scum, and carries with it the impmities. Uses of Gelatine. Gelatine is used as food in form of natural gelatine of soup stock and also for prepared gelatines. In the arts, as in paper-making, it is added to pulp, and the whole is rolled into sheets and dried. It serves to hold pieces together. It is used in paint- ing, printing, and in carbon photography. LEMON JELLY 185 Composition of Gelatine. Gelatine is nitrogenous. In composition it resembles albumen, but it contains less sulphur and more nitrogen. The proportion of nitrogen to carbon is 4 to 11. Nutritive Value. For purposes of nutrition the gelatinoids are inferior to albuminoids, although they are easily digested and so are often given in convales- cence. In combination with albiraiinoids they have a food value. Pure gelatine alone does not support life. Dogs fed upon it die of starvation. Gelatine does not form muscular tissue, but it economizes the al- buminoids. Since gelatine extracted from bones is identical with that from other parts (bones being richer in gelatine than other parts) and since bones 5deld two- thirds of their weight of it, it is an advantage to make them serve as nutrition in the form of soups, etc. However, a proper proportion of the other principles must be supplied, viz., J meat soup to f gelatine soup. Gelatine alone requires something to make it digestible, for it is too neutral and too insipid to set the digestive juices at work. Properties of Gelatine. When pure, gelatine is taste- less and odorless, insoluble in cold water, soluble in boiling water and dissolved at 200°, solidifies on cook- ing, is decomposed by much boiling and then will not solidify on cooking; therefore it should not be cooked.

AI-modernized reading of the original text

Glue is common in impure gelatine obtained from animal substance, especially from parings of ox or other thick hides, ears of oxen and sheep, skins of rabbits, hares, cats and dogs, parings of leather, parchment, old gloves, etc. It is steeped with limewater to remove blood and fatty parts, and is then . dried and stored. After washing, it is put into vats in an open boiler with water, and thus the gluey parts are dissolved from the leather. Samples are taken and tested in water to see if they are clean. If heated at or above boiling-point too long it loses the power of congealing. Boiling separates the impurities; after the glue has solidified it is sliced and dried for several days. It is transparent and has glassy fracture. It is used as cement for joining wood, etc. When any connective tissue, including bone-cartilage and gristle, is boiled for a long time, a solution is obtained which when cooked forms a jelly. Half of the solid parts of the animal are convertible into gelatine by boihng with water. Calves' feet produce gelatine on comparatively little boiling, older parts on more boiling. Parts of an old animal are not so soluble as of the young. From the several connective tissues various gelatines are then obtained. From ordinary connective tissues we get collagen, from bones ossein, from cartilage choudrin, from superficial tissues (skin, nails, etc.) kreatin; all are forms of gelatine. The species of gelatine fibroin is obtained by boiling spiders' webs, silk of silk-worm, etc. Both tissues are liquid in the animal and solidify on exposure. Fibroin is also found in fibres of sponges. Chitin is the basis of bodily structure in insects. It forms the skeleton of crabs and lobsters and is not so soluble as gelatine of meats. Preparation of Gelatine. The parts are cleaned, cut small, and then boiled with water for some time. Attention is paid to the purity of the product. It is sometimes purified with charcoal or with ox's blood. The albumen of blood coagulates, rises as scum, and carries with it the impurities. Uses of Gelatine. Gelatine is used as food in form of natural gelatine of soup stock and also for prepared gelatines. In the arts, as in paper-making, it is added to pulp, and the whole is rolled into sheets and dried. It serves to hold pieces together. It is used in painting, printing, and in carbon photography. LEMON JELLY 185 Composition of Gelatine. Gelatine is nitrogenous. In composition it resembles albumen, but it contains less sulphur and more nitrogen. The proportion of nitrogen to carbon is 4 to 11. Nutritive Value. For purposes of nutrition the gelatinoids are inferior to albuminoids, although they are easily digested and so are often given in convalescence. In combination with albiraiinoids they have a food value. Pure gelatine alone does not support life. Dogs fed upon it die of starvation. Gelatine does not form muscular tissue, but it economizes the albuminoids. Since gelatine extracted from bones is identical with that from other parts (bones being richer in gelatine than other parts) and since bones 5deld twothirds of their weight of it, it is an advantage to make them serve as nutrition in the form of soups, etc. However, a proper proportion of the other principles must be supplied, viz., J meat soup to f gelatine soup. Gelatine alone requires something to make it digestible, for it is too neutral and too insipid to set the digestive juices at work. Properties of Gelatine. When pure, gelatine is tasteless and odorless, insoluble in cold water, soluble in boiling water and dissolved at 200°, solidifies on cooking, is decomposed by much boiling and then will not solidify on cooking; therefore it should not be cooked.

Domestic science (Clark, Cornell home economics)