REDUCTION OF IRON ORES.

781

After an exposure of ten hours to a bright heat, thePyrometer was found to indicate 28°, and the iron-stonehad lost in weight 42 per cent., or 10 per cent, morethan when roasted in the common way. This I attri-buted to the loss of oxygen, in consequence of the me-tallic particles being exposed in contact with carbon-aceous matter. The iron-stone, when washed, andperfectly freed from this substance, was of a greyish-bluecolour, adhesive to the tongue, possessed of a metallictaste, and when pulverized, deflagrated in flame.

400 grains of the common roasted iron-stone, for thesake of comparison, were fused alone, and afforded adense, shining, opaque glass, without any metallic sepa-ration.

400 grains of the cemented deoxydated ore were re-duced to the same size, and fused under the same cir-cumstances, from which resulted a prismatic colouredbutton of iron, weighing 120 grains ; or 30 per cent.The marked difference between these two results I alsoattributed to the presence and absence of oxygen in thetwo ores.

In another experiment I find that 4281 grains of thesame iron-stone in pieces, were exposed for 24 hours incontact with coke dust, to a heat that, by the pyrometer,indicated 69° of Wedgewood; loss in weight equal to43 per cent. So that 14 hours of longer exposure, anddouble the temperature, had only produced a furtherdeoxydation of 1 per cent, beyond that obtained in the

first

cementation. The pieces of iron-stone were now

completely metallic, compact, and brightened under thefile. . .

300 grains of this deoxydated iron-stone yielde yfusion per se, a mass of soft malleable iron, weighinggrains; or 371 per cent. ,

300 grains, to which were added 15 of co e us ,yielded by fusion 163 of iron; or 54| per cen . ive