Iron „ 7$ 
acids, each of which gives up a proportion of oxygen to 
the metal chiefly before separation is effected. 
Does it not then unquestionably follow, that if die quan- 
tity of charcoal in the furnace formerly was sufficient to 
take up the oxygen existing in the ore, and to afford car- 
bonated crude-iron, that if a further quantity of this 
principle is added, by whatever means, part of the char- 
coal which formerly went to carbonate the iron now com- 
bines with the superadded oxygen to form carbonic acid ; 
of course the metal will be deprived of its carbon, become 
white in the fracture, and may then justly be denominated 
oxygenated crude-iron. The same application to princi- 
ple would also inform the merely practical man, that 
when iron-stone is completely deprived of those substan- 
ces which assume the gaseous state by the combination 
of caloric at a moderate temperature, it is then sufficiently 
prepared for the furnace. This is always indicated by 
the colour which the stone assumes varying from a brown 
to a dark claret. Blues always succeed this shade ; and 
the smallest appearance of blue, however light, is a cer- 
tain sign that the external air has made an impression up- 
on the particles of metal, by superoxygenating them. In- 
stead therefore of expelling a further quantity of heteroge- 
neous matter, a principle is added the most noxious and 
destructive to the existence of iron in a metallic form. 
The phenomenon of iron-stone becoming heavier in the 
fire, would no longer be explained by assuming vague as- 
sertions incompatible with and inadmissible to com- 
mon sense. Upon finding two pieces of iron-stone in the 
same fire, which have to appearance been affected in a 
widely different manner by the heat ; the one heavy, of a 
black blueish colour ; the other light and porous : the 
practical man would now no longer say that the metal from 
the porous piece had escaped by these pores, and entered 
into the ponderous one ; and that the accumulation of 
