^°^^-] on Aluminium. 459 



tI,Pv^W.!^f ff '''' T, °°'^ *^''°r '''''° " '*•■§« revolving drum, wben 

 urLrl r . r";" \^^ '"'^"'- ^^"^ '^'■"■^ '^^•"g opened and partially 



J~r f tr. /'"^ ''""'' ?' "''^ '° "^« '''^^"•'^'J temperat,u-e, the 

 wd ^' furnace are all closed to prevent the access of ai •, the 



Ce ft,rn^?r f '' ''"1^^ '^":T"y "'^'' "^« '^^■^t''^ °f ti« dearth. 

 mfen,W^ r f '' "^'"""^^^ "'"^ ^"§''' '^°PP«''«' ^°'^ tl^^ough these 

 Xtnf f»l ', "^', '' introduced as quickly as possibfe. The 



hauefies ''^Z^^^ ^^T'^'^'^''''^^^^ ^"'^ "^^ whole charge quickly 

 liqueies. At the end of a certain time the heating gas is a<rain 



TotZ T tt' '''rf.^^P* ^* % r''^'^'^ ten^peratufe for abCt 

 two horns. At the end of this period the furnace is tapped by drivina 



with a firTcf ? '°"''7P«'''°g' ^W<=h Has previously been^top^S 

 with a fire-clay plug, and the liquid metal run out in a silver stream 



rwroff tl 'Jr" ^"'7 "^1 "P'^'^'^S- ^'^^ «- metalts all b?en 

 removed ' Tbf '^ '' •['"owed to run out into small iron wagons and 



ready for .^^fV^T"^" ''T^ '«^". P'"§§'^'' "?' *'^« f"™^«e is 

 1200 it T ?^^':i ^?'" ''"'^ ''^"■'S'^' <=omposed of about 



1^00 lbs of pure chloride, 600 lbs. of cryolite, and 350 lbs of 

 sodium, about 115 to 120 lbs. of aluminium is obtained 



chloride C7»f/'"'-,r"!^ '"'''".y ^'P'""^' "PO'^ *« P""ty of the 

 metlllf ' n "'i*""' '^^^'■'''^'"g "nore than ordinary care the 

 metal ests usually indicate a purity of m'etal above 99 per cent. On 

 the table is the metal run from a single charge, its weight is 116 lbs 

 and IS composition, as shown by analysis, is 99-2 aluminium 



^nl ' ™/ °'A "■™- ^^'^ ^ ^«"«^<* to be the largest and the 



purest mass of metal ever made in one operation. 



melted dow?in^f^^* " Dine charges are laid on one side, and then 

 me ted down in the furnace to make a uniform quality, the liquid 

 metal, after a good stirring, being drawn off into moulds These 



W t'nf, ' Iff'"! "''""^ '^'^ ^^- '''''^' ^'' '^^^ to tlo cas in/shop 

 there to be inelted and cast into the ordinary pigs, or other shanes a.' 

 may be required for the making of tubes, sheets! or wire or else uLed 

 directly for making alloys of either copper or ir;n. ^ 



m„f: • 7 *°"°"™g t^ble shows approximately the quantity of each 

 material used m the production of one ton of aluminium :- 



Metallic sodium , . a qoa tl. 



Double chloride .. .' 92 4aV 



Cryolite .. ;; - - ^2,400 „ 



Coal «,000 , 



o tons. 



To produce 6,300 lbs. of sodium is required :— 



Caustic soda ........ 44 qOO lbs 



Carbide made from pitch, 12,000 Ibs'l ' 



and iron turnings, 1,000 lbs '/ 7,000 „ 



Crucible ca.ti.gs ;.• ;; ^^i tons. 



Vol. XII. (No. 83.) " " 2 i 



