660 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



iroii flue P. ' represents the walls of the furnace. The wall plaeedjabove the slag- 

 gutter U, which is always considered as the front part of the furnace, is called the 

 front wall. The opposite wall, at the rear, is the back wall; on each side are the side 

 walls, in which apertures are provided for the feed-holes. A wooden hood, W, and 

 chimney, W, are placed in front of the furnace and above the slag-gutter to cairy off 

 the fumes from slags. The crucible A is formed of strong cast-iron plates, a, firmly 

 screwed and bolted together, and it is covered with a cast-iron plate, d (see Figs. 3 

 and 5, Plate XXIX). The crucible is lined with fire-brick or steep (brascjue). In 

 front of the crucible projects the fore-hearth A", to which is adapted the slag-gutter U. 

 Ou one side of the crucible is placed the lead-pot L, communicating with the hearth or 

 crucible A' (Figs. 1, 2, and 3, by means of the siphon //.' This arrangement is called 

 the siphon-tap or automatic tap. It constitutes one of the greatest improvements 

 ever introduced in the construction of blast furnaces, for by its means lead keeps 

 always at the same level and thus escapes as much as possible the oxidizing action of 

 the blast The lead pot is always inclosed in a cast or wrought iron box or frame, a', 

 projecting outside of the crucible. The portion of the hearth designated by A" (Fig. 

 3) is the dam. X' is the steep of which the hearth, fore-hearth, and lead-pot are made. 



The water-jackets B constitute also one of the greatest improvements ever in- 

 troduced in the construction of blast-furnaces. When properly cared for they never 

 get injured; occasionally they may get shifted or spring a leak between the joints, but 

 this rarely affects the jackets themselves. It is sufficient to state that smelting cam- 

 paigns of thirteen mouths are known in the camp, to give an idea of the importance of 

 this arrangement. The water-jackets 'B are hollow boxes, indicated in elevation. Fig. 

 l,aud in section, Fig. 3. They are made of cast-iron, wrought-iron, or steel boiler-plates. 

 In the furnace now under description they are made of cast iron. In the water- 

 jackets water can circulate freely, so that the temperature of this portion of the furnace 

 wall, where the most intense heat reigns in the interior, never exceeds 00 to 70 C. 

 The water-jacket arrangement is always sectional, so as to afford every facility for the 

 removal of the jackets when the furnaces need important repairs. The sectional dis- 

 position admits of the expansion and contraction of this portion of the furnace with- 

 out altering the relative positions of the parts, and on this account must be highly 

 commended. 



In the furnace under description there are twelve jackets: two in front, called 

 the front or breast jackets ; two at the back; and four on each side. In horizontal 

 section, Fig. 2, the manner in which they are formed is shown very clearly. The jackets 

 are firmly screwed, bolted, and braced together. Each jacket is provided with one or 

 more circular apertures for the introduction of the nozzles of the tuyeres. In Fig. 2 

 the arrangement and disposition of the tuyeres N is plainly seen. Each jacket is 

 provided with a cast-iron feeder, B, forming an integral portion of the jacket and cast 

 with it, for the introduction of water. The level of this feeder is higher than the upper 

 part of the jacket, so as to till it completely with water. Small pipes, 8, screwed to 

 the feeders, act as outlets for 'the hot water, which is carried away by the water- 

 gutter T. Gold water is introduced in the feeders by means of the taps Y supplied 

 from the main water-pipe, M. In Leadville the tuyeres are never provided with any 

 special arrangement for cooling them by water, for the reason that the water-jackets 

 act as perfect coolers of the tuyeres. The tuyeres are generally made of thin gal 



