92 FRANK HEARNE CROCKARD 



heavy tonnage involved it was found necessary to have a 

 quicker and more rcHable, as well as a cheaper and less labo- 

 rious, method of handling the iron than that afforded by the 

 old system of casting in pig beds. To meet this demand 

 several well known machines have been devised, one of which, 

 the Uehhng, is built by the American Casting Machine Co., 

 at the Edgar Thomson works. The pigs weigh from 110 

 to 115 pounds, and being free from sand are much more accept- 

 able than the sand laden pigs of our forefathers. Slag ma- 

 chines of the Hawdon type have also been installed in several 

 plants where the local conditions seemed to warrant this par- 

 ticular method of slag disposal. As long as the slag dump 

 affords sufficient room, the ladle car will likely continue as 

 the cheapest and quickest method of disposing of what is 

 still very largely a waste product. In this connection it is 

 interesting to note that several furnace plants, notably the 

 Illinois Steel company, are making a high grade Portland 

 cement from their furnace slag. 



Another feature of the modern furnace deserving special 

 mention is the water cooled bosh plate. As late as 1890 we 

 could not point to a single furnace which had produced 

 250,000 tons during the life of a lining ; to-day we have rec- 

 ords exceeding 1,000,000 tons. Early experiments with 

 water cooled cast iron plates built into the bosh walls dem- 

 onstrated the efficiency of this method of preserving bosh 

 walls. These iron blocks were, however, rather difficult 

 to replace when making renewals, and as a result of continued 

 efforts toward improvement along these lines we have to-day 

 several well known forms of bronze or copper bosh plates, 

 which are built into the bosh walls. In the case of the well 

 known Scott plate they are built into the walls with a re- 

 lieving arch of brick thrown over each plate. In other cases, 

 as with the Gay ley, these arches are dispensed with. In 

 more recent practice an iron arch or socket plate which acts 

 as a holder for the water block has been adopted. The larger 

 plates formerly used have given way to a greater number of 

 smaller plates ; the total amount of copper in a given furnace 

 is not increased by this arrangement, but a more thoroughly 

 protected bosh is the result. At the tuyere belt these plates 



