so 
Iron . 
3d!y. As to the kinds and proportions of earths, wld: 
which the iron ore is mixed. 
As to the state of the iron as it is contained in the ore. 
Iron ores contain the iron either combined with sub 
phur : or with sulphur and arsenic ; or mixed with copper 
ore ; or with manganese : or in the state of an ochre or 
oxyde : or in the state of what the chemists call an oxy« 
dole, frequently magnetic and more approaching to the 
metallic state : or combined with acids, and forming sa- 
line substances, such as green vitriol, &c. 
The sulphuretted ores, are usually called Pyrites ; they 
are often of a metallic gold colour, hard, and brittle, giv~ 
insr fire with steel. These are seldom worked, unless to 
collect the sulphur, or to make green vitrioL But seve- 
ral ores worth working, contain also sulphur, or arsenic, 
or both. This can be ascertained by reducing them to 
powder, and exposing them to a cherry-red heat, when 
the smell will generally detect both the sulphur and the 
arsenic. The fumes of the latter also, will whiten copper. 
Ores much mixed with copper, can seldom be worked 
with profit in a furnace. The mixed metal is brittle and 
bad. Some ores at Cornwall furnace, (Mr. Coleman’s) 
are of this kind, and are not worked. 
Ores are very often mixed with a notable proportion of 
manganese, as I have seen them at the Dunham works* 
that formerly belonged to Jos. Galloway. This mixture' 
is a detriment, though of late it has been proposed to give 
the properties of steel to iron by means of manganese, in a 
large way. These ores are blackish, and give a full green 
slag with common white glass and potash as a flux. 
Nickel, Crome, and Phosphorus are also frequently com- 
bined with iron, but it requires much chemical skill to 
separate them accurately. In a large way, they must be 
separated in the bloomery and by the hammer. 
The oxydes of iron, and the iron combined with carbo- 
