148 REPORT — 1869. 



and the bottom part tendered moveable and capable of being withdi-awn on 

 wheels, without disturbance to the supports &c. of the remaining upper por- 

 tion of the converter. Ready means of temporary attachment by clamps and 

 cotters are provided to connect the two parts, which thus so far present a 

 close resemblance to the Calebasse cupola still in use in Belgium. At one side 

 of the cyliudric fixed part of the converter, a sort of hopper, with a loosely 

 hinged iron-plate cover, is provided, which communicates with the cavity 



within. 



" The lower part, or " converting-pot," has a cylindrical cavity with a flat 

 bottom, and with the sides near the top edge sloping inwards to a cone all 

 round. The cavity, up to the level of the lower edge of this cone, is prepared 

 to just hold the bulk of crude nitrate of soda required for the volume of liquid 

 iron to be operated on, and for the latter when converted ; the proportion of 

 nitrate, as at present employed by the patentee, being 2 cwts. to the ton of 

 liquid iron, or 10 per cent.— a proportion, we may remark, which both the 

 metallurgists who have been engaged in examining this process by the pre- 

 sent owners of the patents are of opinion is a good deal in excess of what 

 is needed, when the conditions for the most favourable reaction shall be more 

 completely and more scientifically understood. The " converting-pot " is 

 lined with fire-brick and refractory clay. When the crude nitrate is filled 

 in and levelled up to, or a trifle beyond, the narrow part of the conical lining, 

 the cast-iron perforated plate is simply laid upon its level surface, and worked 

 round a httle until its edges bed firmly into and upon the clay lining. In 

 this state the converting-pot is rolled in under the upper part of the converter, 

 clamped up to it, and the whole is now ready for work. 



" The charge of cmde cast iron is melted A\-ith coke in an ordinary cupola ; 

 at present it is tapped out into a crane-ladle. This is swung round by the 

 crane, and the contents at once emptied into the opened hopper of the con- 

 verter. The molten iron falls upon the cold cast-iron plate ; its lowermost 

 stratum is for the moment chilled and nearly consolidated by the heat with- 

 drawn by contact, and for some minutes there is no perceptible action. In 

 this state a vertical section of the charged and filled converter is repre- 

 sented by fig. 1. Soon, however, tl\e lower stratum recovers its liquidity, and 

 begins to penetrate below the now more than red-hot and softened perforated 

 cast-iron plate, and reaction commences, evidenced by the appearance of white 

 and grey vapours at the top of the converter-funnel. The nitrate has no 

 doubt by this time got much impacted and partly fused at its upper strata. 

 The reaction producing a large accession of heat at the plane of contact of 

 the molten iron and of nitrate, the plate melts and disappears. A burst 

 of brilliant yellow flame at the top of the converter-funnel indicates that 

 the reaction is then at its height. This lasts steadily for some few minutes 

 (three to five usually, with 12 or 15 cwt. charges), and then rajudly subsides. 

 The conversion is now complete. The bottom of the converter, or " converting, 

 pot," is now detached and roUed away, and the converter is ready for another 

 bottom and another charge. 



" When we examine the converting-pot withdrawn, we find its surface 

 covered to the depth of an inch or two with a dark " blabby slag," through 

 which brilliant jets of yellow sodium-coloured flame from escaping gases are 

 constantly sparting. This slag consists chiefly of the soda of the nitrate, 

 combined with silica and clayey matters derived from the hning of the con- 

 verter, and involving some " shots " of metallic iron or steel, and some little 

 silicate of iron, &c. Eencath this is the converted metal, which the patentee 

 calls " crude steel." It forms a white-hot, howsovjlee, and tolerably liquid 



