172 Hot Blast in the Smelting of Lead. 
The air by thus passing through the hollow chest, becomes 
heated, and being thrown in this state through the mass of burn- 
ing sulphuret, reduces it in a great measure, by the combustion 
of its own fuel, the sulphur, the quantity of wood consumed 
being less than one fourth of a cord for the product of 2000 lbs. 
pig lead. The fuel used is wood only, and that of the lightest 
kind ; coal or other concentrated fuel gives a heat too intense near 
the blast, and reduces the product in a given time, from one third 
to one half. 
In operating the furnace, it is necessary to charge it about once 
in ten minutes, which is done by drawing the ‘charge’ forward 
upon the hearth, (the blast having been previously shut off by a 
valve, to protect the smelters,) billets of wood are thrown in, in 
front of the ‘twyer,’ and the charge thrown back with the requisite 
quantity of fresh mineral, when the blast is again let on. The 
furnaces continue to run thus, without intermission, night and 
day for six days in the week. 
The economy and efficiency of this furnace will be understood 
from the following facts. In smelting about 5,000,000 lbs. of 
lead at the Rossie smelting works, the average product at each 
furnace was about 7,500 lbs. for each day of twenty four hours. 
Number of men employed, two at a time, four in all at each fur- 
nace. Amount of wood consumed, three fourths of a cord per 
day. The cost of mere smelting, not reckoning use of works, 
cost of creating blast or superintendence, was as follows : 
Two smelters at $1,50 per day, . , $3,00° 
Two assistant do. 1,00 « » 2,00. 
Three fourths cord prepared wood, at '$2,00 1,50 
6,50 
for a jrédlae of 7,500 Ibs. or about $1,75 per ton. . 
Preparation of the ore.—W here saving of labor is so great an ob- 
ject as it is in this country, it may not be uninteresting to describe 
the method and machinery used for preparing the ore at Rosse. 
The smelting works are situated at a water power upon Indian 
Ete at a convenient distance from the mines. ‘The ore in the 
lies in a matrix of calc spar, through which it is scattered 
rysta sof all sizes and proportions, from galena with a small 
per cent. of gai a ng ue, , to ) gangue with a very small per cent. of gale- 
t a large proportion of the diggings require to be crushed 
and washed in order to procure the whole product of the mines. 
