1020 IRON 



perature of the crucible, and facilitate the solidification of the loupe or bloom. An ori- 

 fice n,fys. 1283, 1284, called the chio (floss-hole), allows the melted slag or cinder to 

 flow off from the surface of the melted metal. A copper pipe or nose piece conducts 

 the blast of both bellows into the hearth, as shown at b x,fig. 1284. 



The substance subjected to this mode of refinery is a grey carbonaceous cast iron, 

 from the works of Rothehutte. The hearth D, being filled and heaped over with livo 

 charcoal, upon the side opposite to the tuyere x,figs. 1283, 1284, long pigs of cast iron 

 are laid with thoir ends sloping downwards, and are drawn forwards successively into 

 the hearth by a hooked bar, so that the extremity of each may be plunged into 

 the middle of the fire, at a distance of 6 or 8 inches from the mouth of the tuyere. 

 The workman proceeds in this way till he has melted enough of metal to form a loupe. 

 The cast iron, on melting, falls down in drops to the bottom of the hearth ; being 

 covered by the fused slags, or vitreous matters more or less loaded with oxide of 

 iron. After running them off by the orifice n, he then works the cast iron by power- 

 ful stirring with a rabble, till it is converted into a mass of a pasty consistence. 



During this operation, a portion of the carbon contained in the cast iron combines 

 with the atmospherical oxygen supplied by the bellows, and passes off in the form of 

 carbonic oxide and carbonic acid. When the lump is coagulated sufficiently, the 

 workman turns it over in the hearth, then increases the heat so as to melt it afresh, 

 meanwhile exposing it all round to the blast, in order to consume the remainder of 

 the carbon, that is, till the iron has become ductile, or refined. If one fusion should 

 prove inadequate to this effect, two are given. Before the conclusion, the workman 

 runs off a second stratum of vitreous slag, but at a higher level, so that some of it may 

 remain upon the metal. 



The weight of such a loupe or bloom is about 2 cwts., being the product of 2 cwts. 

 and ^ths of pig-iron ; the loss of weight is therefore about 26 per cent. 149 pounds of 

 charcoal are consumed for every 100 pounds of bar iron obtained. The whole ope- 

 ration lasts about 5 hours. The bellows are stopped as soon as the bloom is ready ; 

 this is immediately transferred to a forge-hammer, the cast-iron head of which 

 weighs 8 or 9 cwts. The bloom is greatly condensed thereby, and discharges a 

 considerable quantity of semi-fluid cinder. The lump is then divided by the hammer 

 and a chisel into 4 or 6 pieces, which are re-heated, one after another, in the same 

 refinery fire, in order to be forged into bars, whilst another pig of cast iron is laid in 

 its place, to prepare for the formation of a new bloom. The above process is called 

 by the Germans Klump-frischen, or lump refining. It differs from the Durchbrech- 

 frischen, because in the latter the lump is not turned over in mass, but is broken, 

 and exposed in separate places successively to the refining power of the blast near the 

 tuyere. The French call this affinage par portions ; it is much lighter work than the 

 other. 



Charcoal Finery or Lancashire Hearth. Wo are indebted for the following accurate 

 account of this important finery to Dr. Percy, who gives it in his work on iron and 

 steel: 



The furnace (figs. 1285 and 1286) consists essentially of a shallow quadrangular 

 hearth, formed of cast-iron plates a, b t c, d, and e. The hearth-bottom a, is horizontal ; 

 the tuyere side b, slightly inclined inwards ; the opposite side 11, and the back c, inclined 

 outwards ; the front e is vertical, and in it there are three round holes for tapping off 

 the cinder. Under the hearth-bottom is an open shallow cast-iron box, having a 

 gutter on one side/, and a round hole in the centre of the bottom/, surrounded with 

 a border not quite so high as the box is deep. The box and gutter are cast in one 

 piece. During the working of the furnace cold water is continually flowing through 

 / and running out at/; by this arrangement the hearth-bottom is kept cool. The 

 side walls above the hearth are protected within by cast-iron plates, (figs. 1285 and 

 1286). Hot blast is used, and there is one iron water tuyere t, nearly semicircular in 

 section, which passes through a thick cast-iron plate set in one of the side plates g. 

 The narrow end projects over the side of the hearth f inch, and the axis is inclined at 

 an angle of about 10 with the horizon. As the charcoal is confined round and above 

 the tuyere, the plate g is exposed to great heat, and consequently destruction ; it is 

 made very thick, and may bo readily replaced when required. In front of the hearth 

 is a table or platform of cast iron A, resting on the ends of cast-iron standards. This 

 table is essential for the necessary manipulations. The arrangement for heating and 

 conveying the blast to the tuyere is represented at k, K k". The heating apparatus 

 consists merely of a siphon-pipe of cast iron, set horizontally and exposed to the waste 

 gases of the furnace. There is a throttle valve at k for stopping and regulating the 

 blast ; the nozzle end of the blast-pipe may be raised or lowered at will by a telescope 

 sliding piece, and may bo turned in any direction by means of the union joint below k 

 (fig. 1286). The waste gases escape partially through the square opening I ; at m is 

 a cast-iron plate, on which pigs or blooms are laid so as to become heated ; at n is an 



