1871.] Mineralogy. 541 



in too large pieces, and must be properly distributed through the furnace, 

 whilst from time to time the contents of the furnace require to be gauged. 



We learn from the " Mining Journal," that some little stir has been excited 

 by the recent discovery in Low Furness of an enormous deposit of haematite, 

 estimated by competent authorities at not less than one million tons. 



At the Round Oak Ironworks, belonging to the Earl of Dudley, Howatson's 

 puddling and heating furnaces have lately been tested with excellent results. 

 The peculiarity of these furnaces consists in supplying hot instead of cold air 

 for the combustion of the fuel, whereby a great saving of coal and iron is said to 

 be effected, whilst the working of the furnace is improved and quickened. In 

 the heating-furnaces the cold air is caused to enter a flue or heating chamber 

 surrounding the base of the stack. Having become heated by contact with the 

 sides of this flue, the air traverses a series of horizontal flues, parallel to each 

 other under the bed of the furnace, whence it passes to the ash-hole beneath 

 the fire-grate, and thence through the fire-bars to the fuel. To ensure 

 perfect combustion of the gases from the fuel and to prevent smoke, a vertical 

 flue is made in the side walls of the fire-grate, and is connected with a 

 horizontal flue furnished with perforations above the bars, which admit 

 and distribute the heated air over the fire. 



In the puddling-furnace the cold air is first admitted under the bed of the 

 furnace, which it helps to cool, and then proceeds to a flue surrounding 

 the base of the slack, whence it passes along the sides of the furnace to the 

 end, and finally descends to the ash-pit. 



At the time we write, the Iron and Steel Institute is holding a meeting 

 at Dudley, under the presidency of Mr. H. Bessemer. Some interesting 

 papers on metallurgical subjects are before the Institute, and will be duly noticed 

 in this journal. 



MINERALOGY. 



So rarely has the diamond been found in a veritable matrix that considerable 

 interest attaches to any fresh instance of its occurrence in situ. According 

 to Professor P. von Jeremejew,* of the Mining Institute of St. Petersburg, 

 microscopic crystals of diamond occur as enclosures in the mineral called 

 xanthophyllite. Specimens of this mineral from the Schischimskian moun- 

 tains, in the Slatoust mining district in the Urals, have been found to enclose 

 crystals which present the form of the hexakistetrahedron, combined with a 

 slightly developed tetrahedron — the faces of the first form being distinctly 

 curved, whilst those of the latter are perfectly plane. The greater number of 

 these crystals are colourless and transparent, but some few are tinted brown. 

 Those enclosures are most abundant in the greenish plates of xanthophyllite, 

 which occur in the neighbourhood of nodular aggregates of talcose schist 

 and serpentine ; moreover, these two rocks also enclose similar microscopic 

 crystals. 



From the recent researches of Professor Zepharovich, it appears that two 

 distinct minerals have hitherto been confounded under the common name of 

 Freieslebenite.* It is well known that much difference of opinion has prevailed 

 respecting the crystalline system to which this species should be referred— 

 some authorities placing it in the rhombic, others in the monoclinic, and 

 others again in the triclinic system. Zepharovich now shows that the native 

 compound, Ag 4 Pb 3 Sb 4 Su, is dimorphic, and forms two distinct species, which 

 differ not only in crystalline form, but also in specific gravity. One of these 

 minerals assumes monoclinic shapes, and has a density of 6*35 ; whilst the 

 other crystallises in the rhombic system, and has a density of only 5*9. For 

 the former species the name Freieslebenite is to be retained, whilst for the 

 latter Zepharovich proposes the name Diaphorite, from dicupopa, "a difference." 

 The mineral which has formed so large a part of the ore raised at the silver- 

 mine of Hiendelaencina, in Spain, belongs to the species Freieslebenite, which 

 is found also at Freiberg, in Saxony. Diaphorite occurs at Przibram, in 

 Bohemia, and at Braunsdorf, near Freiberg. 



* Jahrbuch fiir Mineralogie, &c, 1871, Heft 3, p, 275. 

 + Ibid., p. 277. 



