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. (A. B. W. K.; W. E. D.)
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 Good Friday (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. Friedberg in der Wetterau, 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.
See Dieffenbach, Geschichte der Stadt und Burg Friedberg (Darms., 1857).
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.
See a memorial lecture by J. M. Crafts, printed in the Journal of the London Chemical Society for 1900.
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 Napoleonic Campaigns). 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
