FLUORIDES 



3218 



FLUTING t 



been added in order to make the 

 liquid conduct the electric current. 

 One compound of fluorine and 

 hydrogen is known, but no oxide 

 has been prepared. Although 

 fluorine is akin to chlorine in many 

 properties, there are no fluorine 

 compounds corresponding to hypo- 

 chlorites and chlorates. 



Fluorides. Salts of hydro- 

 fluoric acid. They are prepared by 

 acting on a metal, or its oxide 

 hydroxide or carbonate, with 

 hydrofluoric acid. Calcium fluoride 

 (CaF 2 ) occurs native as fluorspar 

 or " blue-John," and from it most 

 of the preparations of fluorine are 

 made. The fluorides of the alkalis 

 are soluble in water and are 

 employed with mineral acids or 

 acetic acid in the processes of 

 etching glass. Some of the fluor- 

 ides are gaseous at ordinary 

 temperatures, but most of them 

 are stable bodies, and are not de- 

 composed by heat. A series of 

 double fluorides is known. Fluor- 

 ides are recognized by the evolu- 

 tion of hydrofluoric acid on heating 

 with sulphuric acid. 



Fluorspar. Common mineral 

 widely distributed in rock crevices. 

 It is a compound of calcium and 

 fluorine and is iiiiiiiimim 



used as a source 

 o f hydrofluoric 

 acid and as a 

 metallurgical flux. 

 When colourless 

 and transparent it 

 is used for lenses ; 

 amethyst, purple, 

 green, or yellow 

 specimens yield 

 "false" amethysts, 

 sapphires, etc. , for 

 cheap jewelry. 

 Derbyshire " blue- 

 John " is made into 

 ornamental vases. 

 The mineral is 

 also found in Cornwall and Cum- 

 berland. In 1920 a new field for 

 the supply of fluorspar was found 

 near Wirksworth, Derbyshire. 



Flushing (Dutch, Vlissingen). 

 Seaport of Holland. On the S. coast 



of the island of Walcheren, it lies 

 at the mouth of the Schelde, hi the 

 province of Zeeland. It is now 

 chiefly noted as the port for com- 

 munication with the ports of 

 Queenborough and Folkestone, 

 Kent (S.E. & C. Rly.), with through 

 rly. connexion to Rotterdam, Am- 

 sterdam, and the N. of Europe 

 generally. Except for shipbuild- 

 ing and some rly. workshops, the 

 town has little trade, but it is of 

 considerable strategic importance, 

 and new fortifications are planned. 

 It had also developed before the 

 Great War as a sea-bathing resort. 



In the history of the Netherlands 

 Flushing was often prominent, 

 especially as a naval base. It was 

 the birthplace of Admiral Buyter, 

 1607, and there is a monument to 

 him in the town. The town was 

 severely bombarded by an English 

 fleet under Lord Chatham hi the 

 Walcheren expedition of 1809, but 

 the subsequent attempt to capture 

 Antwerp from there failed com- 

 pletely. Pop. 21,878. 



Flushing. Suburb of the 

 borough of Queens, New York, 

 U.S.A. Formerly a village of 

 Queens co., it stands on Flushing 

 Creek. Long Island, and was incor- 







Flute. 1. Boehm concert flute, 26 ins. 2. 8-keyed 



concert flute, 26 ins., 17th-19th centuries. 3. Military 



flute in F, 19 J ins. 4. Military fife in B flat, 15 ins. 5. 



Piccolo or octave flute, 12 ins. 



Flushing, Holland. 



porated with the borough in 1908. 

 It contains schools and a public 

 library, and manufactures chemi- 

 cals and cinematograph films. 

 Settled hi 1643, it later became the 

 residence of many Quaker families. 

 Flustra. Group 

 ; of polyzoa. Usu- 

 ally known as sea- 

 j^g^jgtegHf mats, they resem- 

 ble small brown 

 ^.-jjj seaweeds. They 

 BfjHf are common 



around the British 

 ' J^SrSMfil coasts, and con- 

 sist of a horny, 

 leaf-like skeleton, 

 containing vast 

 numbers of tiny 

 cells. Each of 

 these is occupied 

 by a tiny flower- 

 General view ol the quays and port - like polyp with a 



row of tentacles which can be pro- 

 truded from the cell in search of 

 food. 



Flute (Lat. flatus, blast). Family 

 name of many wind instruments of 

 the whistle type, whether blown 

 vertically through a mouthpiece or 

 transversely through a side hole. 



Down to the end of the 18th 

 century the number of flutes em- 

 ployed in the orchestra was uncer- 

 tain, and on account of their weak 

 tone several of them were often 

 used hi unison ; but the modern 

 instruments are so much improved 

 that it is now customary to employ 

 them singly, and the two (or occa- 

 sionally three) flutes of the modem 

 orchestra play independent parts. 

 Flutes have been made at various 

 pitches, but the scale of the open 

 finger-holes is always called D. The 

 transposing of flutes, other than the 

 concert flute of ordinary pitch, has 

 been usually reckoned from D in- 

 stead of from C. Originally, the six 

 finger-holes were the only means of 

 obtaining a scale, and chromatic 

 notes had to be made by cross- 

 fingerings, half stops, and other un- 

 satisfactory means ; but key after 

 key has been added until now all the 

 semitones are producible, in good 

 tune and with even tone. The conve- 

 nient compass of the concert flute 

 is as shown, 



andthree A 



semitones -O. 



higher are pos- 

 s i b 1 e. The 

 flute is the 

 most agile of 

 the wind in- ^ ~*=f 

 struments, 

 modern mech- 

 anism having reduced finger diffi- 

 culties to a minimum. Flute is 

 also the name of an organ stop imi- 

 tating the tone of the orchestral 

 instrument of the same name. See 

 Fife ; Flageolet ; Organ ; Recorder ; 

 consult also History of the Boehm 

 Flute, '1896; Six Lectures on the 

 Recorder, C. Welch, 1911. 



Flute-a-bec. Beaked flute, or 

 flute with a mouthpiece, played 

 vertically. See Flageolet ; Flauto 

 Traverso ; Recorder. 



Fluting. In architecture, the 

 grooves in a column, separated by 

 fillets. The 

 elliptical chan- 

 nels in Doric 

 columns are, 

 however, not 

 called flutes. 

 Fluting is 

 generally ver- 

 t i c a 1, but 

 spiral fluting 

 occurs in Nor- 

 man architec- 



ture. See Fluting of column in 

 Architecture. Canterbury Cathedral 



! ^ 



