BAIRD &.TATLOCK (LONDON) LTD. 



2972 



Electric Cupel Crucible Furnace, for the laboratory, with directing magnet.* 



transactions of the Academy of Sciences, No. 12, 2oth March, 1893. 



Ihis furnace is intended for laboratory experiments and tests. The first type brought out in 1892 was with 

 vertical carbon pencil ; it is based on the Siemens' electric furnace. 



The present type has oblique carbon pencils, movable in metallic mounts (G G). It is easy to bring them into 

 contact or withdraw them from each other. 



As in the first type, the whole forms a closed vaulted chamber with fireproof linings (R), receiving the movable 

 crucible (CR). Channels serve for the circulation of gases or the introduction of materials to be submitted to the 

 action of the electric arc. 



The phenomena of fusion and reduction may be observed direct, the sides of the apparatus having movable 

 covers (or doors) fitted with mica panels. They may be produced with zirconium and thorium, as has been demon- 

 strated by Mr. Troost in carrying out his experiments with this apparatus (Transactions of the Academy o/ Sciences, 

 2gth May, 1893). 



The movable crucible (CR) can be shifted from outside at the will of the operator, the base-plate on which it 

 rests being manipulated by means of the rod (RE) . This crucible is of carbon, graphite, magnesia, limestone, lime, 

 or metal according to the material to be reduced. 



The arc playing between the carbon pencils (C C) may be transformed, at a distance, into an elongated flame 

 forming a veritable electric blowpipe flame, thanks to the directing action of a magnet (Ai) , placed near the apparatus. 

 Thus the arc can be withdrawn, if necessary, at will, or directed upon the material contained in the crucible (CR). 

 This arrangement, devised by us, is a novel application of a known phenomenon already utilised by Jamin in his 

 electrical lamp. Thus the material contained in the crucible is gradually brought to the maximum temperature. 

 (The wooden block supporting the magnet may be dispensed with ; it will suffice to give an inclined position 

 to the magnet while letting it rest direct on the table and the slate base of the apparatus.) 



The small laboratory type, with a current of from 12 to 30 amperes and 55 to 70 volts in the terminals, permits 

 obtaining the reduction of oxides and the fusion of the most refractory metals in sufficient quantities for spectral 

 or chemical analysis. All experiments and laboratory tests demanding a very elevated temperature can be realised 

 with this apparatus. The large type will bear currents of greater intensity ; the pencils (C C) are in this case 

 provided with mountings permitting circulation of water around them. 



NOTE. Do not touch the conductors carrying the electric current to the binding-screws of the crucible, except 

 by taking hold of them in insulated parts ; the currents employed, whether continuous or alternating, may be 

 dangerous to bear. It is useful, moreover, to insert in the circuit near the apparatus a " high-intensity current " 

 switch. To avoid the action of the intense rays of the electric arc upon the eyes or the skin, it is indispensable to 

 protect oneself with special spectacles and screens. 



PRICES. 



2972 T Electric crucible No. i, Small type as per above figure. For crucibles (Cr), in the form 

 of a cupel, from 33 to 35 millimetres outside diameter. Movable base-plate with 

 clamp screw. Slate base on four cast-iron legs. With one carbon crucible (Cr) 

 and one crucible of limestone, Nos. 3 and 5, without directing magnet . . 



(This crucible No. i is for currents from 12 to 30 amperes, 50 to 70 volts ; 

 carbon pencils 10 millimetres in diameter.) 



Prices continued on page 569. 



CROSS STREET HATTOTST GARDETST, E-C 



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