METALLURGY. 159 



These furnaces, although they differ slightly in size, are all constructed in 

 nearly the same manner. The portion of the stack above the smelting 

 zone is constructed of ordinary brick and is cylindrical in form. It is sup- 

 ported by cast-iron pillars, which rest on a solid foundation. The smelting 

 zone itself is composed of a water jacket, or rather several water jackets, 

 called "baches," and is oblong in shape. The "baches" are hollow boxes 

 of boiler plate 30 inches high, 20 inches broad, and 6 inches deep at the 

 top and 4 inches at the bottom. In the center of each is an opening for a 

 tuyere, which may be a water tuyere or merely a pipe to convey the blast. 

 The water tuyeres are long, and are used at those points where it is neces- 

 sary to convey the blast for some distance into the charge. The baches 

 are inclined a little outward at the top on the upper edge of the crucible or 

 lead well. They are joined to the stack above by a course or two of fire- 

 brick luted with clay. They are fastened to each other on the sides by 

 key-bolts, which can be easily removed in case of an accident, such as the 

 burning through of the iron of the bache. This arrangement allows the 

 removal of one of these water jackets and of its replacement by a new one 

 without interference with the working of the furnace. The baches are open 

 at the top and continually receive a stream of cold water which keeps them 

 cool. The iron comes in direct contact with the charge as in all water- 

 jacket furnaces. The furnace has an open hearth at one end with a slag 

 spout as well as one for speiss. The latter is placed one and one-half inches 

 below the former. The lead is allowed to run out of an opening on the 

 side of the lead well, which is a very short distance below the speiss spout. 

 When one of the large furnaces is working properly there is a continuous 

 flow of all the three smelting products, slag, speiss, and lead, from the cru- 

 cible. The furnaces are barred out regularly once every twelve hours, the 

 front bache being removed for that purpose. It is said to have been 

 proved by repeated experiments that the nature of the Eureka ores renders 

 their advantageous smelting in a furnace with a closed hearth impossible, 

 as the large quantity of iron in the ore makes a continual barring out nec- 

 essary in order to prevent the formation of "sows." The separation of the 

 different smelting products, slag, speiss, and lead, is tolerably complete. 



