EEACTIONS IN BLAST FCRXACBS. 741 



It biis buen seen that the normal volume of blast delivered by the blower con- 

 nected with this turnace is 2,550 cubic feet per minute, or 17,850 cubic feet in seven 

 minutes, at the rate of 80 revolutions per minute; consequently, 9,943.8 cubic feet of 

 blast must be shut out during the seven minutes. This is done, as before shown, by 

 leaving open the damper placed at the extreme end of the main blast-pipe. However, 

 there is hardly any doubt that in practice an excess of air passes through to the fur- 

 nace, and it is to avoid this that the adoption of a meter to be placed at the induction 

 pipe has been recommeuded. 



Loss of weight of charges.— The data are now prepared which are necessary for the 

 discussion of the loss of weight of smelting charges in every zone of the furnace in seven 

 minutes, and for giving an idea of the chief reactions that take place in each. As the 

 element of time is all-important in these discussions, the reactions have been de- 

 scribed in zones of temiierature higher than those indicated by theory ; but, if there 

 are a few errors of judgment in the position assigned to them, the final results remain 

 unaltered. 



The weight of gases' which pass through the uppermost zone in seven minutes is 

 as follows: 



Zone of gases 150° C 



Carbonic acid 27. 455 



Oxide of carbon 1S8. 771 



Vapor of water 26.225 



Nitrogen 310.103 



Gases from f ael 2. 955 



Dust and lead fumes 5. 823 



Total ; ; r 501.322 



Zone of desiccation 150° C. 



Weiiiht 'if charge entering zone 502. 5270 



It loses onrfourtb of its moisture (chiefly from the ore), or 5.5058 



It loses one-eleventh of total loss in dust and fumes 0. o-?94 



6. 11332 



Zone of desiccation '255° C. 



Weight of charge entering zone 49G. 4918 



It loses one-fourth of its moieture (chiefly from the ore) 5. 5058 



It loses one-eleventh of total loss in dust and fumes 0. 5294 



Zone of cJesiccafion '3G0° C. 



Weight of charge entering zone 490. 450t> 



It loses one-fourth of its moisture (from ore and fuel) 5. 5057 



It loses one-eleventh of total loss in dust and fumes 0. 5294 



6.0351 



Zone of desiccation 465*^ C. 



Weight of charge entering zone 484. 4215 



It loses the remaining one-fourth of its moisture (chiefly from fuel) 5.5057 



It loses o!ie-eleventh of total loss in dust and fumes 0. 5294 



— 6. 0351 



478. 3864 



'As no analyses were made of the gases passing through the different zones of the furnaces at 

 Leadville, the figures given by Sir. Giiyard in the following tallies cannot lie assumed to represent 

 their actual composition. In point of fact, their composition must he very different from that assumed 

 by him, owing to the excess of blast used. His idea is evidently to represent what the theon tical 

 conditions in the furnace should he wlieu employing the least amount of blast for the given amount of 

 fuel. (S. F. E.) 



