Page:Encyclopædia Britannica, Ninth Edition, v. 9.djvu/364

 350 F L U F L U simple or modified cubes and octahedrons ; also nodular, compact and granular, and more rarely fibrous, or soft and earthy. Some octahedral crystals from the mines of St Agnes, in Cornwall, are made up of minute cubes, which may themselves show faces of other forms of the monometric system of crystallography. Fluor spar is a brittle, trans parent to sub-translucent mineral, with a perfect octahedral cleavage, a vitreous, sometimes splendent lustre, a hardness of 4, and a specific gravity of 3 01 -3 2 5. Before the blowpipe it decrepitates, tinges the flame dull red, and fuses into an enamel. Heated with concentrated sulphuric acid it yields hydrofluoric acid (see CIIEMISTKY, vol. v. p. 491). In colour lluor spar varies much, being blue, purple, green, yellow, pink, or brown ; it is sometimes dichroic. The colours are attributed by Wyrouboff to the presence of minute quantities of hydrocarbons, taken up from solutions from which the mineral has crystallized ; by others they are considered to be due to peculiarities of molecular structure. In the Weardale fluors small cavities containing liquid have occasionally been found. Fluor spar, in common with some other substances, when exposed to light, or when raised to a temperature somewhat under redness, usually phosphoresces, emitting a bright light, the colour of which is not dependent on that of the mineral. A variety of fluor spar has received its name chlorophane from its fine green phosphorescence. Like the colour, the phosphorescence of fluor-spar is destroyed by exposure to a high temperature ; it may be partly restored by means of an electric discharge, or, it is said, by moistening with dilute hydrofluoric acid. From the name of the mineral Professor Stokes borrowed the term fluorescence,&quot; applied by him to the quality which certain bodies, e.g., sulphate of quinine, possess of rendering the ultra-violet rays of the spectrum visible. W. Hankel (Ann. Phys. Chem. [2], ii. 6G-83), experimenting on crystals of fluor spar from Weardale, found that when exposed to light they exhibited not only phosphorescence but electrical phenomena ; the rays of the sun, however, concentrated by a lens, deprived the crystals of their photo- electrical property, which they did not regain. Fluor spar is slightly soluble in water containing hydrated calcium carbonate. Pseudomorphs of hornstone, hematite, calamine, and other minerals after fluor spar are not unfrequent. Fluor spar is commonly used for the production of hydro fluoric acid in etching on seals and glass, and in the smelting of lead and copper and in other metallurgical operations as a flux, whence its name, from the Latin fluo, to flow. The manufacture of vases and other ornamental articles from fluor spar, especially the variegated varieties, has long been carried on iu Derbyshire. The stone, which is some times first heated to change its blue to an amethystine tint, is shaped by means of the lathe and a fine steel tool, and is finished off with coarse stone, and after that with pumice and emery. Fluor spar is of frequent occurrence in metalliferous veins, being most commonly associated with ores of lead, as in the mines of Derbyshire, Cumberland, Cornwall, Saxony, and Bohemia. It is met with also in granite, gneiss, slates, various limestones and sandstones, and some volcanic products, and has occasionally been detected in beds of coal. On the phosphorescence of fluor spar see Prof. C. Bohn s paper on &quot;Negative Fluorescence and Phosphorescence, &quot;Phil, Hag. [41, vol. xxxiv. p. 109, 1867. FLUSHING (Dutch Vlisswyen a fortified seaport town of the province of Zealand, Holland, is situated on the island of Walcheren, at the mouth of the estuary of the Western Scheldt, about 4 miles S. of Middleburg, and 50 miles S.W. of Rotterdam. It possesses an academy of sciences, a school of navigation, a town-hall, a theatre, an exchange, and a statue to Admiral Kuyter, who was born here in 1607. Since 1872 it has had direct railway connexion with the main lines of Europe ; and by the construction in 1873 of a great harbour, docks, and canal works a com munication between it and the North Sea has been opened up for vessels of the largest size. The outer harbour has a surface of 33 - ll acres, and a depth at low water of 22 feet ; the depth of both the inner harbours at low water is 27 feet, the surface of the one being 1 6 5 5 acres and that of the other 11 86 acres. With these works Flushing possesses one of the finest and safest harbours of the Con tinent, and the one on the Dutch coast best adapted for the trade of Holland and Germany. Its chief exports are wheat, beans, fish (especially shrimps), and cattle ; and its chief imports ccal from England, and coffee, tea, and tin from Java. The number of vessels entering and clearing annually is upwards of 100. Besides the shipping trade the chief industries are brewing and the manufacture of oil and soap. Flushing was one of the &quot; cautionary towns &quot; delivered up to Queen Elizabeth in 1 585 in security for the money and soldiers sent by her to assist the Dutch under Sir Philip Sidney. It was captured by the French in 1795, and in 1809 it was bombarded by the English under Lord Chatham, and did not surrender till the fine town-hall, two churches, and about 100 houses were destroyed. Its fortifications have since that time been greatly strengthened, and now completely command the entrance to the river. Population in 1869, 8929. FLUSHING, a post-village of Queens county, New York, is situated on Long Island at the head of Flushing Bay, about 7 miles NE. of New York, and 8 N.E. of Brooklyn. It possesses a State bank, a savings bank, an academy, a female seminary, and several other educational institutions. It is the residence of many of the New York merchants, and is noted for its large gardens and nurseries. Popula tion in 1870, 6223. FLUTE, a wind instrument which in a variety of forms has been in constant use from the earliest ages To Olympus the Phrygian has been ascribed the introduction of flute-playing into Greece, an art which was much encouraged in the later days of the empire. The Greeks employed professional flute-players in many of their religious ceremonies, and competitive trials of skill were frequent. The old English flute, called the flute-ii-bec, from the sup posed resemblance of the mouthpiece to the beak of a bird, was played from the upper and wider end, had seven finger holes, and was made of various sizes, called treble, alto, tenor, and bass flutes respectively. This instrument con tinued in common use to about the middle of the 18th century, when it was gradually superseded by the modern horizontal (flauto traverse) or &quot; German ; flute. Handel was one of the first to introduce the new instrument into the orchestra, employing it for solos in The Ode on Saint Cecilia s Day (1739), notably in the air &quot; The soft com plaining Flute.&quot; But the capacities of the traverse of Handel s time were very limited in comparison with those of its modern representative, which possesses a workable compass of about three octaves from the low C in the treble clef, with all the chromatic intervals. Various systems of fingering have been introduced from time to time by the most eminent flautists and flute-makers, and concertos for the flute as a solo instrument have been composed with a view to exhibiting the powers of celebrated performers. In orchestral scores the flute part is generally placed at the top, and is written in the violin or G clef. The piccolo or octave flute, the E flat or tierce, the D flat or minor ninth (transposing piccolo), the flute d amoitr, a minor third below the ordinary instrument are all varieties of the IraVerso, which like the fife is blown by an oval shaped hole in the side, near the stopped end of the tube. Other branches, now obsolete, of the flute family were the recorder, varying in length of tube from about twelve