Iron . 
149 
7thly, That much trouble and ex pence may be saved by 
thus mixing ores of different qualities. So too, the rich 
primary iron ores, that are not enveloped in earth, may be 
frequently mixed with good effect with the secondary ores, 
where the distance will allow the expence of carriage. By 
the primary ores, meaning such as are found in or near 
the strata called primitive by the mineralogists, such as 
hematitic iron ore, heavy compact red iron-stone and 
similar ores, which may be mi ted with the common ear- 
thy iron-stones to good effect especially in charcoal fur- 
naces. This is done in England where the Lancashire 
and Cumberland ores are so mixed with the poorer iron- 
stones in the coak furnaces. 
8thlv, That the limestone earth to become a flux, 
should be added in proportion as much at least as the 
predominant earth of the ore to which it is applied. I hus ? 
if the iron be enveloped when put in the furnace in clay 
and sand-stone of which the clay is about 2 parts and the 
sand-stone one, the limestone should be 2 parts also, or 
equal to the clay : this rule applies, not to the whole weight 
of the iron stone, but merely to the earths mingled with it. 
9thly, The more moisture your ore, and your charcoal 
contains, the more fuel and air, you must use to get rid of 
it : and also, 
lOthly, The more moisture your ore and your charcoal 
contains, the more fuel is carried off in forming steam, 
and is wasted in combining with the oxygen that is formed 
by the decomposition of the water, which contains by 
weight 85 parts of oxygen in 100. 
lOthly, If your charcoal be not well burnt, it employs 
the contiguous charcoal in the furnace to burn it ; where- 
in there is waste. 
llthiy, The use of the charcoal or coak, (the fuel) is 
threefold. It is employed to give heat and bring every 
thing into liquid fusion : and it is employed to supply 
carbon to decompose the ore, and abstract from it its oxy- 
