452 
Iron . 
thus changing the metallic portion of the ore into a sub-sulphuret 
of iron. The ore in this state is conveyed to the furnace and 
thrown into a situation where scarcely a particle of free oxygen 
can be conveyed to it, until it has descended nearly its whole dis- 
tance, and where of course it has but little chance of losing any 
portion of its sulphur except what the hydrogen of the charcoal 
may dissolve and dissipate. The greater part therefore, una- 
voidably remains in combination to the last, changing nearly the 
whole into cinder and debasing to the most worthless degree the 
small portion of iron which can under such circumstances be pro- 
duced from it. In the assay crucible I have found the effect ex- 
actly similar, when the flux used was properly adapted to support 
the analogy between the small and the large way of operating. 
The effect of Mr. Mushet’s proportions of flux, and the reasons 
why those proportions have probably led to such erroneous infer- 
ences will come more methodically before us in a future pa- 
per. 
The injurious effects of too great a degree of heat on an irorn 
stone which does not contain sulphur, are simply that it wastes 
fuel unnecessarily — that the ore is afterwards less easy to pound 
than if properly roasted — and lastly, that the increased density 
and hardness of the mass makes it probably more difficult for the 
vapour of cementation to pervade, and this contraction I have 
generally attributed to the large proportion of clay with which 
these ores are always united. 
Thus it is best in all cases that the ore should not be fused. 
But with a sulphureous ore this circumstance is of the greatest 
importance. Sulphur, and nothing else will account for the dif- 
ference, nor can I perceive that oxygen has any thing to do with 
it. 
The relation winch the magnetic property bears to the value 
and richness of iron ores, and the reasons why torrefaction exhibits 
this property in so remarkable a degree, will form the subject of 
my next communication. J. H. H. 
Remarks by the Editor . 
The preceding paper is well worth attention on a very impor- 
tant part of the process of smelting iron ores. 
The ores of iron, appear as ores and not as pure iron, in con- 
sequence of the iron contained in them being combined, with sul- 
phur or arsenic or both— -or with oxygen in various proportions or 
