92 president's address — section b. 



constituents. N'ow. the prime object in blowing is to effect a complete 

 absorption of the oxygen blown in, and in good practice this is achieved. 

 A iriven pressure, therefore, corresponds to a certain depth of m-^.tte : 

 so that a low pressure corresponds to a shallow column and a simul- 

 taneous retardation of the work, and a higher pressure corresponds 

 to the more appropriate opposites. As a matter of fact, this special 

 purpose of elev^ttting the tuyeres, so that a low pressure shall suffice, 

 is scarcely heeded by the operatives, who much prefer to dig the tuyeres 

 as deeply as they can into the matte, and to penetrate as high a column 

 as possible, so as to ensure intenscr action. Structurally, too, the 

 horizontal cylindrical shape is one of the least secure constructions 

 that could be devised, which is particularly true of its top. Ex- 

 perience corroborates this, for in addition to the greater difficulty of 

 putting the lining in firmly, as compared with the upright form, the 

 insecure top lining has more frequently to be changed ; and the prox- 

 imity of the roof to the bath also greatly aggravates its abrasion. 

 The lining is, however, the sorest point about the whole operation, and 

 should not be abused. The main advaiitage in favor of the roller-born 

 horizontal type is an ordinary manipulative '">ne. Especially where 

 cranes are used, the ease and despatch with which the vessel can be 

 lifted off and on to its bearings, its accessibility, and general handiness 

 (except for lining), have made it por)ular in its current American designs. 

 Its size hj.s grown to great limits. The later French forms are l.-44m. 

 long by 1 .44m. diameter, but even thp first trough converter introduced 

 in America (1893) was 5ft, 8in. in diameter by 8ft. lonj. Those at 

 the recently finished Washoe Works at Anaconda are 8ft. diameter 

 bv 12.|ft. long, and have an initial capacity of 7 short tons of matte, 

 with a final cavity capable of holding 12 tons. The Kio Tinto vessels 

 are 7ft. diameter by 15ft. length, and have an initial capacity of -3 tons 

 to 4 tons, and a final one of 8 tons. For special purposes the horizontal 

 converter has been made 8ft. diameter by 20ft. long. 



The Bottom-Blown Upright Vessel. — Notwithstanding the mo- 

 mentary vogue of the horizontal converter, there are indications that 

 even the old bottom-blown upright converter may, in due course, be 

 reinstated, or rather -since the early trials were only crudely con- 

 ducted in the light of present skill — may eventually be properly appre- 

 ciated. The Great Falls 7ft. by 13ft. converter, when provided with 

 16 |in. tuyeres in the bottom, s:uccessfully brought matte to blister 

 in a very much shorter time than the side-blown vessels, and with a 

 far more even corrosion of the lining, both of which points are the 

 natural results of the better distribution of the air. A current of blast 

 entering froni below is divided into a stream of bubbles in ascending 

 the bath. A side-blown current is more Hkely to break through in 

 gulps. The latter also corrodes the lining, by preference in the im- 

 mediate vicinity of the tuvere openings, and naturally, since the tuyere 

 holes are in the back of the vessel only, chiefly on that side. The vertical 

 converter is, in fact, in America looked forward to as the future form, 

 provided the difficulty of making the bottom tuyeres stand is overcome. 

 In large charges the drawback of blowing through the metallic copper 



