1004 



TIN 



Ores introduced by hopper, at the rate of 1 quintal to every revolution of table. 



Quantity of ore calcined per day of 10 hours, 30 to 35 quintals. 



Salt consumed, generally six per cent, of weight of ore. 



Fuel consumed per 10 hours, 1,200 to 1,400 Ibs. of pine-wood. 



Power employed to revolve table, half horse. 



1988 



Remarks. The furnace is charged with ore and salt by means of iron hoppers 

 placed immediately over the centre of each of the hearths. For the supply of each 

 hopper, a heap of about 14 quintals of ore, with 5 or 6 per cent, of salt, is prepared 

 from time to time upon a small platform on the top'of the furnaces, and a few shovels- 

 ful thrown in occasionally as required, taking care, however, always to have enough 

 ore in the hopper to prevent the ascension of acid vapours, &c., from the furnace. The 

 time the mineral remains in the furnace, and the quantity calcined per hour, must 

 depend on the rapidity of motion of the revolving hearth, and the angle at which tJie 

 iron stirrers are fixed. 



The average amount passed through each furnace in 24 hours is about 84 quintals 

 or 3 quintals per hour. For every revolution of the bod, nearly 1 quintal is discharged 

 'from the furnace. 



The smelting of tin ores has been effected by two different methods : 



