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LVIII. Note on a Crystallized Compound of Sesquioxide of Iron 

 and Lime. By John Percy, M.D., F.R.S., Lecturer on Me- 

 tallurgy at the Royal School of Mines, London*. 



IN 1861 1 published the following statement f : — "Sesquioxide 

 of iron and lime. I find that a mixture of these substances 

 in certain proportions yields a well-melted slag*. A mixture con- 

 sisting of 160 grains of pure sesquioxide of iron and 100 of 

 white marble ( = 56 grains of lime) — that is, in the ratio of 

 Fe 2 O 3 : CaO — was exposed in a covered clay crucible to a high 

 temperature. It was perfectly melted, and when broken across 

 resembled a black, opaque, vitreous slag : the crucible had one 

 large perforation. In a second experiment a mixture, according 

 to the same formula, of 40 grains of sesquioxide of iron and 25 

 of carbonate of lime was heated in a clay crucible lined with 

 platinum-foil. It was perfectly melted, and escaped through 

 the crucible." As in these experiments the heating of the cru- 

 cible was effected in an air-furnace, and as the product was not 

 analyzed, it was conceived that some of the sesquioxide of iron 

 might have been reduced to protoxide, with the formation of 

 a proportionate quantity of magnetic oxide, which, it is well 

 known, is fusible at a high temperature ; for H. Rose found that 

 when sesquioxide of iron was heated per se in a porcelain kiln, it 

 was reduced to magnetic oxide, which melted. In order to settle 

 the point, the following experiments have been made. An inti- 

 mate mixture of 190 grains of sesquioxide of iron and 66*5 grains 

 of lime (i. e. in the ratio above mentioned) was kept heated to 

 whiteness in a platinum vessel during several hours in a muffle, 

 the atmosphere in which is oxidizing, and left to cool in the 

 furnace during the night. The product appeared to have been 

 perfectly melted, and consisted of a mass of interlacing acicular 

 crystals exceeding an inch in length; it had a dark bright 

 metallic lustre ; it was very brittle, and when in the state of fine 

 powder resembled brown iron ore in colour; its fracture was 

 uneven and lustrous ; its specific gravity was 4*693 ; and, what 

 is interesting, it was magnetic. 



Its composition per cent, was as follows : — 



Sesquioxide of iron . . 73*39 



Protoxide of iron . . . 72 



Lime 24*50 



Silica 1*35 



Alumina 0*10 



100*06 



* Communicated by the Author. 

 t Metallurgy, vol. i. p. 43. 



