Iron . 
53 
In order to elucidate still farther how much the quality of 
the iron is dependent upon the proportions of the mixtures., 
in combination with or given to the ores, let a determinate 
quantity, say an ounce, of the oxyde of pure malleable 
iron be taken this we are physically certain contains no 
mixture except oxygen existing in quantity proportioned 
to the stage of oxydation, the quantity being ascertained 
by its degree of obedience to the magnet ; when the quan- 
tity of oxygen given to it, by the decomposition of water, 
exceeds 25 per cent . few traces of magnetic attraction are 
perceptible : —introduce this oxyde into a covered cruci- 
ble, without any addition, and expose it to a violent de- 
gree of heat for 40 minutes, {longer in proportion to the 
quantity,) a button of highly oxygenated crude iron will 
be obtained : if the heat is continued longer than is ne- 
cessary to effect this, a small mass of malleable iron will 
be found occupying the bottom of the crucible. The 
produce in either case will be short of the real quantity of 
metal contained in the oxvde. When oxygenated crude 
iron is obtained, the ore from which it is produced, to use 
the common phraseology, is said to contain bad iron . 
That this has no relation to truth, will be seen by taking 
another portion of the same oxyde : let it be mixed either 
with chalk or lime, and a little bottle-glass, to constitute 
fusibility, and expose to a similar degree of heat with the 
former ; the whole contents in iron will then be found re- 
the philosopher’s stone of the iron manufactory ; to its presence is 
attributed the production of bad iron— -when the metal is in its most 
valuable state, it is also sulphury it prevents cast iron from be- 
coming malleable, and if sulphur were altogether absent, hard or 
white cast iron could not be produced. If cast iron is found colon r- 
ed, it is by the sulphur ; is it crystallised and coloured, then it has 
sulphur to excess ; should it have lost its strength, or have become 
loose in the fracture by an excess of shrinkage in large castings, 
still it is by the agency of sulphur : in short, in every process in 
the manufacturing* of iron, sulphur explains the whole phenomena ! 
it is execrated in one process, and anxiously looked for in another,, 
