Page:The American Cyclopædia (1879) Volume XII.djvu/619

OILS AND FATS posed of three proximate, principles, stearine, palmitine, and oleine, the first two being solid at ordinary temperatures, the last liquid. The mixture of the three therefore varies in soft- ness according to the proportion of oleine which it contains. These proximate principles are compounds of the triatomic alcohol glyce- rine, acting as a base, and stearic, palmitic, and oleic acids, and may therefore be regarded as organic salts. It is to the investigations of Chevreul, made about 1820, that we owe our fundamental knowledge of the fatty bodies. Since then others, and particularly Berthelot, have extended his researches, and in the main confirmed their correctness. The nature of these bodies was well defined by Chevreul, but he regarded them as compounds of stearine, oleine, and margarine. It has however been shown by Heintz that Chevreul's margarine is not a simple fat, but a mixture of palmitine and stearine; for when it is saponified, the acid obtained from the soap is found to be a mixture of palmitic and stearic acids. The natural oils and fats may be heated to nearly 500 F. without much change ; but they can- not be distilled without decomposition, by which they are distinguished from the volatile oils, the latter evaporating and distilling at va- rious temperatures. At about 500 they begin to evolve acrid and offensive vapors, and at about 600 they are decomposed with evolu- tion of gaseous hydrocarbons. When heated with caustic alkalies they undergo a peculiar change called saponification or conversion into . soap, during which process glycerine is libera- ted, while the alkali combines with the oleic, stearic, and palmitic acids. (See SOAP.) All the natural oils and fats are soluble in ether, and to a certain extent in alcohol. Oil of tur- pentine and benzole also readily dissolve them, and they mix with each other in all propor- tions. The fixed oils are divided into drying and non-drying oils. Drying oils when ex- posed to the air thicken from absorption of oxygen, being converted when spread upon surfaces into a tough transparent membrane or varnish. Linseed, nut, hemp, and poppy oils belong to this class, and contain an oleine which differs from that of the non-drying oils, yielding by saponification, instead of oleic, lin- oleic acid or one similar to it. (See DRYING OILS, and LINSEED OIL.) The non-drying oils are also gradually altered by exposure to the air, but in a different way ; they lose much less fluidity, become acid, and acquire an acrid, disagreeable taste. This alteration, however, never takes place in pure glycerides, as pure stearine, palmitine, or oleine, or mixtures of them ; but only when other organic matters, such as the cellular substance of the plant or animal in which the oil naturally exists, are present. These substances contain nitrogen, and act as ferments, producing decomposition of a part of the fatty matter with which they are mixed ; by this action stearic, palmitic, and oleic acids are set free, and small quantities of OJIBWAYS 605 certain volatile acids, as butyric, valerianic, and caproic, are formed, probably from atmos- pheric oxidation. By treatment with boiling water, and afterward in the cold with a weak alkaline solution, rancid oils may be purified and restored to their original condition. The uses of the fatty oils are extensive. The dry- ing oils are used in the preparation of paints, varnishes, and cements. They are also used in medicine, often in the forms of liniment, as linseed oil in the lime-water liniment, or the linimentum calcis of the pharmacopoeia, an excellent application to burns and abrasions of the skin. The non-drying oils are used in the manufacture of soap, for lubricating machine- ry, for illumination by various methods, for the preparation and preservation of food, and also in medicine. OISE (anc. Isara and Esia), a river of France, which rises in the province of Hainaut in Bel- gium, near the French frontier, flows S. W. through the departments of Le Nord, Aisne, Oise, and Seine-et-Oise, and joins the Seine 12 m. K. W. of Paris, after a course of about 150 m. Its principal tributaries are the Noirieu, Brche, and Therain on the right, and the Ton, Serre, Lette, Aisne, Autonne, and Nonette on the left. It communicates by canals with the Somme, the Sambre, and the Scheldt. The principal towns on its banks are La Fre, Noyon, Compidgne, and Pontoise. OISE, a N. department of France, formed from parts of the old provinces of Isle-de- France and Picardy, bordering on Somme, Aisne, Seine-et-Marne, Seine-et-Oise, Eure, and Seine-Inferieure ; area, 2,261 sq. m. ; pop. in 1872, 396,804. The chief rivers are the Oise and its tributaries the Aisne, Nonette, and Therain. The Epte passes through the W. part, and the Ourcq through the S. E. The surface is low and undulating, and the- soil consists in general of strong clay, but there are sandy barrens. The chief crops are wheat, flax, hemp, and rape. The wine is of inferior quality, and there are few vineyards. Wool- lens, linen, canvas, and beet sugar are manu- factured. The department is divided into the arrondissements of Beauvais, Clermont, Com- piegne, and Senlis. Capital, Beauvais. OJIBWAYS, or Chippewas, a tribe of the great Algonquin family, living in scattered bands on the shores of Lake Huron and Lake Superior, La Pointe being the central point. They be- came known to the French about 1640, the earliest band reached being that at Sault Ste. Marie, from which fact they received the name Sauteux, still applied to them by the Canadian French. In 1642 Fathers Jogues and Raym- baut began a mission at Sault Ste. Marie, where they numbered 2,000. The Ojibways are tall, well developed, good-looking, brave, expert hunters, little given to agriculture, and fond of adventure. From early times they were at war with the Foxes, Sioux, and Iroquois. They drove the Sioux from the head waters of the Mississippi and from the Red river of the North,