271 
cular arrangement of the particles ; but why certain ores and 
fuel should invariably produce an iron which has a strong 
tendency to the fibrous molecular arrangement, and other 
ores have as constant a tendency to the crystalline or cold 
short molecular arrangement, is a question which I have 
never been able to obtain the slightest explanation of. It is 
true that sulphur is said to contribute to the one, phosphorus 
to the other ; but why ? 
Hardness This certainly depends in a great degree on 
more or less of carbon being left in the malleable iron, but 
also, I imagine, sometimes on the presence of other bodies, 
among which are silica or silicium, sodium, or chloride of 
sodium, and potassium. It also may depend on the specific 
gravity of the. iron, which we know may be manufactured so 
as to present either a very compact or a very porous texture ; 
and accordingly the specific gravity of both iron and steel has 
been found to vary considerably in different qualities. Soft- 
ness may arise from extreme purity. The charcoal iron of 
Biscay, in Spain, is, I believe, considered the purest iron 
made, elsewhere than in the laboratory of a chemist ; it cer- 
tainly is the softest. 
A subject like that which I have brought before you this 
evening might be indefinitely prolonged. There are a great 
variety of irons used for special purposes in Birmingham, 
which I have not named, nor have I even alluded to the 
multitudinous descriptions of irons which are employed in 
the manufacture of steel of various qualities ; but at this 
point I have read over and timed my paper, and I find 
that it will occupy so much of our meeting this evening as 
only to leave time for the remarks of some of our members, 
much more competent than myself to have undertaken the 
subject. 
A short discussion followed, after which the Chairman 
called for the next paper announced to be read, which was — 
