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 motion. That the friction at the higher velocities occurring in engineering practice is much less than at common velocities has been shown by several modern experiments, such as those of Sir Douglas Galton (see Report Brit. Assoc., 1878, and Proc. Inst. Mech. Eng., 1878, 1879) on the friction between brake-blocks and wheels, and between wheels and rails. But no increase in the coefficient of friction had been detected at slow speeds, until the experiments of Prof. Fleeming Jenkin (Phil. Trans., 1877, pt. 2) showed conclusively that at extremely low velocities (the lowest measured was about .0002 ft. per second) there is a sensible increase of frictional resistance in many cases, most notably in those in which there is the most marked difference between the friction of rest and that of motion. These experiments distinctly point to the conclusion, although without absolutely proving it, that in such cases the coefficient of kinetic friction gradually increases as the velocity becomes extremely small, and passes without discontinuity into that of static friction.  FRIDAY (A.S. frige-dæg, fr. frige, gen. of frigu, love, or the goddess of love—the Norse Frigg,—the dæg, day; cf. Icelandic frjádagr, O.H. Ger. friatag, frigatag, mod. Ger. Freitag), the sixth day of the week, corresponding to the Roman Dies Veneris, the French Vendredi and Italian Venerdi. The ill-luck associated with the day undoubtedly arose from its connexion with the Crucifixion; for the ancient Scandinavian peoples regarded it as the luckiest day of the week. By the Western and Eastern Churches the Fridays throughout the year, except when Christmas falls on that day, have ever been observed as days of fast in memory of the Passion. The special day on which the Passion of Christ is annually commemorated is known as (q.v.). According to Mahommedan tradition, Friday, which is the Moslem Sabbath, was the day on which Adam was created, entered Paradise and was expelled, and it was the day of his repentance, the day of his death, and will be the Day of Resurrection.  FRIEDBERG, the name of two towns in Germany. 1. A small town in Upper Bavaria, with an old castle, known mainly as the scene of Moreau’s victory of the 24th of August 1796 over the Austrians. 2., in the grand duchy of Hesse-Darmstadt, on an eminence above the Usa, 14 m. N. of Frankfort-on-Main, on the railway to Cassel and at the junction of a line to Hanau. Pop. (1905) 7702. It is a picturesque town, still surrounded by old walls and towers, and contains many medieval buildings, of which the beautiful Gothic town church (Evangelical) and the old castle are especially noteworthy. The grand-ducal palace has a beautiful garden. The schools include technical and agricultural academies and a teachers’ seminary. It has manufactures of sugar, gloves and leather, and breweries. Friedberg is of Roman origin, but is first mentioned as a town in the 11th century. In 1211 it became a free imperial city, but in 1349 was pledged to the counts of Schwarzburg, and subsequently often changed hands, eventually in 1802 passing to Hesse-Darmstadt.  FRIEDEL, CHARLES (1832–1899), French chemist and mineralogist, was born at Strassburg on the 12th of March 1832. After graduating at Strassburg University he spent a year in the counting-house of his father, a banker and merchant, and then in 1851 went to live in Paris with his maternal grandfather, Georges Louis Duvernoy (1777–1855), professor of natural history and, from 1850, of comparative anatomy, at the Collège de France. In 1854 he entered C. A. Wurtz’s laboratory, and in 1856, at the instance of H. H. de Sénarmont (1808–1862), was appointed conservator of the mineralogical collections at the École des Mines. In 1871 he began to lecture in place of A. L. O. L. Des Cloizeaux (1817–1897) at the École Normale, and in 1876 he became professor of mineralogy at the Sorbonne, but on the death of Wurtz in 1884 he exchanged that position for the chair of organic chemistry. He died at Montauban on the 20th of April 1899. Friedel achieved distinction both in mineralogy and organic chemistry. In the former he was one of the leading workers, in collaboration from 1879 to 1887 with Émile Edmond Sarasin (1843–1890), at the formation of minerals by artificial means, particularly in the wet way with the aid of heat and pressure, and he succeeded in reproducing a large number of the natural compounds. In 1893, as the result of an attempt to make diamond by the action of sulphur on highly carburetted cast iron at 450°-500° C. he obtained a black powder too small in quantity to be analysed but hard enough to scratch corundum. He also devoted much attention to the pyroelectric phenomena of crystals, which served as the theme of one of the two memoirs he presented for the degree of D.Sc. in 1869, and to the determination of crystallographic constants. In organic chemistry, his study of the ketones and aldehydes, begun in 1857, provided him with the subject of his other doctoral thesis. In 1862 he prepared secondary propyl alcohol, and in 1863, with James Mason Crafts (b. 1839), for many years a professor at the Massachusetts Institute of Technology, Boston, he obtained various organometallic compounds of silicon. A few years later further work, with Albert Ladenburg, on the same element yielded silicochloroform and led to a demonstration of the close analogy existing between the behaviour in combination of silicon and carbon. In 1871, with R. D. da Silva (b. 1837) he synthesized glycerin, starting from propylene. In 1877, with Crafts, he made the first publication of the fruitful and widely used method for synthesizing benzene homologues now generally known as the “Friedel and Crafts reaction.” It was based on an accidental observation of the action of metallic aluminium on amyl chloride, and consists in bringing together a hydrocarbon and an organic chloride in presence of aluminium chloride, when the residues of the two compounds unite to form a more complex body. Friedel was associated with Wurtz in editing the latter’s Dictionnaire de chimie, and undertook the supervision of the supplements issued after 1884. He was the chief founder of the Revue générale de chimie in 1899. His publications include a Notice sur la vie et les travaux de Wurtz (1885), Cours de chimie organique (1887) and Cours de minéralogie (1893). He acted as president of the International Congress held at Geneva in 1892 for revising the nomenclature of the fatty acid series.  FRIEDLAND, a town of Bohemia, Austria, 103 m. N.E. of Prague by rail. Pop. (1900) 6229. Besides the old town, which is still surrounded by walls, it contains three suburbs. The principal industry is the manufacture of woollen and linen cloth. Friedland is chiefly remarkable for its old castle, which occupies an imposing situation on a small hill commanding the town. A round watch-tower is said to have been built on its site as early as 1014; and the present castle dates from the 13th century. It was several times besieged in the Thirty Years’ and Seven Years’ Wars. In 1622 it was purchased by Wallenstein, who took from it his title of duke of Friedland. After his death it was given to Count Mathias Gallas by Ferdinand II., and since 1757 it has belonged to the Count Clam Gallas. It was magnificently restored in 1868–1869.  FRIEDLAND, the name of seven towns in Germany. The most important now is that in the grand duchy of Mecklenburg-Strelitz, on the Mühlenteich, 35 m. N.E. of Strelitz by the railway to Neu-Brandenburg. Pop. 7000. It possesses a fine Gothic church and a gymnasium, and has manufactures of woollen and linen cloth, leather and tobacco. Friedland was founded in 1244 by the margraves John and Otto III. of Brandenburg.  FRIEDLAND, a town of Prussia, on the Alle, 27 m. S.E. of Königsberg (pop. 3000), famous as the scene of the battle fought between the French under Napoleon and the Russians commanded by General Bennigsen, on the 14th of June 1807 (see ). The Russians had on the 13th driven the French cavalry outposts from Friedland to the westward, and Bennigsen’s main body began to occupy the town in the night. The army of Napoleon was set in motion for Friedland, but it was still dispersed on its various march routes, and the 