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 of the saponification value (see above) and of the optical rotation, and in special cases the isolation and quantitative determination of characteristic substances, leads in very many cases to reliable results. The colour, the boiling-point, the specific gravity and solubility in alcohol serve as most valuable adjuncts in the examination with a view to form an estimate of the genuineness and value of a sample. Quite apart from the genuineness of a sample, its special aroma constitutes the value of an oil, and in this respect the judging of the value of a given oil may, apart from the purity, be more readily solved by an experienced perfumer than by the chemist. Thus roses of different origin or even of different years will yield rose oils of widely different value. The cultivation of plants for essential oils has become a large industry, and is especially practised as an industry in the south of France (Grasse, Nice, Cannes). The rose oil industry, which had been for centuries located in the valleys of Bulgaria, has now been taken up in Germany (near Leipzig), where roses are specially cultivated for the production of rose oil. India and China are also very large producers of essential oils. Owing to the climate other countries are less favoured, although lavender and peppermint are largely cultivated at Mitcham in Surrey, in Hertfordshire and Bedfordshire. Lavender and peppermint oils of English origin rank as the best qualities. As an illustration of the extent to which this part of the industry suffers from the climate, it may be stated that oil from lavender plants grown in England never produces more than 7 to 10% linalool acetate, which gives the characteristic scent to lavender oil, whilst oil from lavender grown in the south of France frequently yields as much as 35% of the ester. The proof that this is due mainly to climatic influences is furnished by the fact that Mitcham lavender transplanted to France produces an oil which year by year approximates more closely in respect of its contents of linalool acetate to the product of the French plant.

.—For the fixed oils, fats and waxes, see C. R. A. Wright, Fixed Oils, Fats, Butters and Waxes (London, 2nd ed. by C. A. Mitchell, 1903); W. Brannt, Animal and Vegetable Fats and Oils (London, 1896); J. Lewkowitsch, Chemical Technology and Analysis of Oils, Fats and Waxes (London, 4th ed., 3 vols., 1909; also German ed., Brunswick, 1905; French ed., Paris, vol. i. 1906. vol. ii. 1908, vol. iii. 1909); Laboratory Companion to Fats and Oil Industries (London, 1902); Cantor Lectures of the Society of Arts, Oils and Fats, their Uses and Applications; Groves and Thorp, Chemical Technology, vol. ii.; A. H. Gill, Oil Analyses (1909); G. Hefter, Technologie der Fette und Öle (Berlin, vol. i. 1906; vol. ii. 1908); L. Ubbelohde, Handbuch der Chemie und Technologie der Öle und Fette (Leipzig, vol. i., 1908); R. Benedikt and F. Ulzer, Analyse der Fette und Wachsarten (Berlin, 1908); J. Fritsch, Les Huiles et graisses d’origine animale (Paris, 1907).

For the essential oils, see F. B. Power, Descriptive Catalogue of Essential Oils; J. C. Sawer, Odorographia (London, 1892 and 1894); E. Gildemeister and F. Hoffmann, Die aetherischen Öle (Berlin, 1899), trans. (1900) by E. Kremers under the title Volatile Oils (Milwaukee, Wisconsin); F. W. Semmler, Die aetherischen Öle nach ihren chemischen Bestandteilen unter Berücksichtigung der geschichtlichen Entwickelung (Leipzig); M. Otto, L’Industrie des parfums (Paris, 1909); O. Aschan, Chemie der alicyklischen Verbindungen (Brunswick, 1905); F. R. Heussler (translated by Pond), The Chemistry of the Terpenes (London, 1904).

 OIRON, a village of western France, in the department of Deux-Sèvres, 7 m. E. by S. of Thouars by road. Oiron is celebrated for its château, standing in a park and originally built in the first half of the 16th century by the Gouffier family, rebuilt in the latter half of the 17th century by Francis of Aubusson, duke of La Feuillade, and purchased by Madame de Montespan, who there passed the latter part of her life. Marshal Villeroy afterwards lived there. The château consists of a main building with two long projecting wings, one of which is a graceful structure of the Renaissance period built over a cloister. The adjoining church, begun in 1518, combines the Gothic and Renaissance styles and contains the tombs of four members of the Gouffier family. These together with other parts of the château and church were mutilated by the Protestants in 1568. The park contains a group of four dolmens.

 OISE, a river of northern France, tributary to the Seine, flowing south-west from the Belgian frontier and traversing the departments of Aisne, Oise and Seine-et-Oise. Length, 187 m.; area of basin 6437 sq. m. Rising in Belgium, 5 m. S.E. of Chimay (province of Namur) at a height of 980 ft., the river enters France after a course of little more than 9 m. Flowing through the district of Thiérache, it divides below Guise into several arms and proceeds to the confluence of the Serre, near La Fère (Aisne). Thence as far as the confluence of the Ailette its course lies through well-wooded country to Compiègne, a short distance above which it receives the Aisne. Skirting the forests of Compiègne, Halatte and Chantilly, all on its left bank, and receiving near Creil the Thérain and the Brèche, the river flows past Pontoise and debouches into the Seine 39 m. below Paris. Its channel is canalized (depth 6 ft. 6 in.) from Janville above Compiègne, to its mouth over a section 60 m. in length. Above Janville a lateral canal continued by the Sambre-Oise canal accompanies the river to Landrecies. It communicates with the canal system of Flanders and with the Somme canal by way of the St Quentin canal (Crozat branch) which unites with it at Chauny. The same town is its point of junction with the Aisne-Oise canal, by which it is linked with the Eastern canal system.

 OISE, a department of northern France, three-fourths of which belonged to Île-de-France and the rest to Picardy, bounded N. by Somme, E. by Aisne, S. by Seine-et-Marne and Seine-et-Oise, and W. by Eure and Seine-Inférieure. Pop. (1906) 410,049; area 2272 sq. m. The department is a moderately elevated plateau with pleasant valleys and fine forests, such as those of Compiègne, Ermenonville, Chantilly and Halatte, all in the south-east. It belongs almost entirely to the basin of the Seine—the Somme and the Bresle, which flow into the English Channel, draining but a small area. The most important river is the Oise, which flows through a broad and fertile valley from north-east to south-west, past the towns of Noyon, Compiègne, Pont St Maxence and Creil. On its right it receives the Brèche and the Thérain, and on its left the Aisne, which brings down a larger volume of water than the Oise itself, the Authonne, and the Nonette, which irrigates the valley of Senlis and Chantilly. The Ourcq, a tributary of the Marne, in the south-east, and the Epte, a tributary of the Seine, in the west, also in part belong to the department. These streams are separated by ranges of slight elevation or by isolated hills, the highest point (770 ft.) being in the ridge of Bray, which stretches from Dieppe to Précy-sur-Oise. The lowest point is at the mouth of the Oise, only 66 ft. above sea-level. The climate is very variable, but the range of temperature is moderate.

Clay for bricks and earthenware, sand and building-stone are among the mineral products of Oise, and peat is also worked. Pierrefonds, Gouvieux, Chantilly and Fontaine Bonneleau have mineral springs. Wheat, oats and other cereals, potatoes and sugar beet are the chief agricultural crops. Cattle are reared more especially in the western districts, where dairying is actively carried on. Bee-keeping is general. Racing stables are numerous in the neighbourhood of Chantilly and Compiègne. Among the industries of the department of manufacture of sugar and alcohol from beetroot occupies a foremost place. The manufacture of furniture, brushes (Beauvais) and other wooden goods and of toys, fancy-ware, buttons, fans and other articles in wood, ivory, bone or mother-of-pearl are widespread industries. There are also woollen and cotton mills, and the making of woollen fabrics, blankets, carpets (Beauvais), hosiery and lace (Chantilly and its vicinity) is actively carried on. Creil and the neighbouring Montataire form an important metallurgical centre. Oise is served by the Northern railway, on which Creil is an important junction, and its commerce is facilitated by the Oise and its lateral canal and the Aisne, which afford about 70 m. of navigable waterway.

There are four arrondissements—Beauvais, Clermont, Compiègne and Senlis—with 35 cantons and 701 communes. The department forms the diocese of Beauvais (province of Reims) and part of the region of the II. army corps and of the académie (educational division) of Paris. Its court of appeal is at Amiens. The principal places are Beauvais, the capital, Chantilly, Clermont-en-Beauvoisis, Compiègne, Noyon, Pierrefonds, Creil and Senlis, which are treated separately. Among the more populous places not mentioned is Méru (5317), a centre for fancy-ware manufacture. The department abounds in old churches, among which, besides those of Beauvais, Noyon and Senlis, may be mentioned those at Morienval (11th and 12th centuries), Maignelay (15th and 16th centuries), Crépy-en-Valois (St Thomas, 12th, 13th and 15th centuries), St Leu d’Esserent (mainly 12th