IRON 1001 



bettor quality of iron, with less percentage of waste : at the same time a larger 

 quantity of iron may be worked with ease in each heat, thus effecting a saving of 

 fuel, time, and labour, and the workmen being relieved, lessens the liability of the 

 underhands absenting themselves from work in hot weather, or when the iron is grey, 

 through which so much loss is sustained in almost every work, and the puddler is 

 still enabled to change his rabble as readily as before, and work in the ordinary way, 

 independently of the machine. The machine, as represented, is made to bolt to the 

 back side of the front furnace-plate, and its action is as follows : The chain giving 

 motion to the shaft, the crank by the connecting-rod working the lever, and the rabble 

 being attached, is drawn from back to front, and is made to traverse from one jamb 

 to the other, by the worm on the shaft turning the worm-wheel connected to the jib 

 by the connecting-rod ; thus every turn of the wheel alters the position of the jib, and 

 the rabble is sent in another direction, but never in the same direction, owing to the 

 wheel having an uneven number of teeth, therefore every part of the furnace bottom 

 is worked over. It is under perfect control, the hand lever throwing in and out of 

 gear the clutch on the side of the chain pulley, thus starting and stopping it at will. 

 It does in no way interfere when the furnace is being rebuilt. 



In a future page mechanical contrivances introduced by Dr. Siemens and Mr. Banks 

 will be especially noticed. 



Ths ' Boiling ' Process. In this operation, which was the invention of Mr. Joseph 

 Hall, pig-iron is converted into malleable iron without the intervention of the refinery, 

 and without any excessive waste: it is, therefore, of great value, especially as it 

 allows of the use of better qualities of pig-iron than those usually employed. The 

 construction of the 'boiling' furnace does not materially differ from that of the 

 'puddling' furnace, except in the depth of the hearth, that is, in the distance from 

 the work plate below the door to the bottom plate, which, in the former, is double, or 

 nearly so, that of the latter. In the puddling furnace the distance between the bottom 

 and top seldom exceeds twenty inches, while in the boiling furnace it varies from 

 twenty to thirty. In puddling the furnace is charged with metal alone, but in boiling 

 cinder is charged along with the metal, and the temperature rises much higher. The 

 bottom of the furnace is covered with broken cinders from previous workings, or 

 with the tap cinder from the puddling furnace, which has been subjected to a process 

 of calcination in kilns ; this material, which constitutes an admirable protection to the 

 iron plates of the furnace, is called by the workmen ' bull dog ; ' its preparation was 

 patented by Mr. Hall in 1839. It is made in the following manner: the tap cinder 

 from the puddling furnace is placed in layers in a kiln, and so arranged that a 

 draught shall pass through from the fire-holes on one side to those of the other ; the 

 kiln is filled up to the top with broken cinders, and over the whole is laid a layer of 

 coke ; about the third or fourth day, the more fusible part of the cinder begins to run 

 out of the bottom holes, leaving in the kiln a fine rich porous silicate of iron, which is 

 the substance used for lining the boiling furnace, the fluid portion being rejected. 

 In 8 or 10 hours the ' bull dog ' is melted by the intense heat of the furnace, covering 

 the bottom, and filling up all the interstices in the brickwork ; the heat is now some- 

 what lowered by diminishing the draught, and the charge of pig (from 3 to 4 cwts.) 

 introduced in fragments of a convenient and iTniform size, together with 30 or 40 Ibs. 

 of cinder ; the doors of the furnace are now closed, and all access of cold atmospheric 

 air prevented, throwing fine cinder or hammer slag round the crevices, and stopping 

 up the work-hole with a piece of coal. In about a quarter of an hour the iron begins 

 to get red hot ; the workman then shifts the pieces so as to bring the whole to a state 

 of uniformity as regards heat. In about half an hour the iron begins to melt ; it is 

 constantly turned over, and at intervals of a few minutes cinder is thrown in ; the sur- 

 face of the mass is seen to be covered with a blue flame ; it soon begins to rise ; a kind 

 of fermentation takes place beneath the surface, and the mass, at first but 2 inches 

 high, rises to a height of 10 or 12 inches, and enters into violent ebullition. During 

 the time that this ' fermentation ' is taking place, constant stirring is required to pre- 

 vent the iron from settling on the bottom. The boiling lasts about a quarter of an 

 hour ; after which the cinder gradually sinks, and the iron appears in the form of 

 porous spongy masses of irregular size, which are constantly stirred to prevent their 

 adhering together in large lumps, to facilitate the escape of the carbon, and to sepa- 

 rate the cinder which, when the operation has been successfully conducted, flows over 

 the bottom apparently as liquid as water. The iron is now ' balled up,' as in the 

 operation of puddling. The objections to the boiling process are : the wear and tear 

 in the furnace which occurs in treating grey pig-iron, particularly that of the more 

 fluid description ; the slowness of the operation, and the amount of manual labour 

 which it entails to produce good results. In some works the crude iron is run 

 directly into the boiling furnace from the blast-furnace, by which much saving of coal 

 is effected, and a product of a more uniform quantity obtained : but the labour of the 



