The iron-ore of the Salem districts of the Madras Presidency is a rich magnetic oxide, very heavy and massive. The yield averages 60 per cent. of metallic iron. Much of the ore being a pure black magnetic oxide, would doubtless yield 73 per cent. The ore is, however, often mixed with quartz, which is a very refractory material in the blast furnace. Limestone, and in some places shell-lime, is employed as a flux ; and the charcoal of some kind of acacia is the fuel. It occurs therein immense beds 50 to 100 feet thick, and its outcrop can be traced for miles. On one hill six miles from Salem are five bands of magnetic iron-ore from 20 to 50 feet thick.
Magnetic iron-ore of fine quality occurs in Coimbatore, Cuddapah, and Vellore ; magnetic hmmatites and magnetic iron-sand also in Cud dapah, in the North Arcot district, in the Vellore taluk, at the villages of Pankam, Pulle putt, Anchenamput, Vannanthangal, Vennembutt, Catharercoopum, Vaniembaddy, Satghar, and Stievelliputur ; and magnetic iron-ores occur in the Bellary, Masulipatam, and Mysore districts. Man ganese was detected in the iron-ores of Hyderabad, Kurnool, Bellary, the Baba-Booden hills, Mysore, and Vizianagram. Ores of Hyderabad are mag netic. In the Salem district two varieties of iron are obtained, one remarkable for its softness and malleability, the other for its steel-like hardness, which adapts it for the formation of edge-tools, cold chisels, etc. The following names are given to this metal in process of adaptation to its finished manufacture :—Culties or blooms of iron, Palms or bars of iron, Vuttoms or pieces of cast-steel as it comes from the clay crucibles, Oollies or bars drawn out from the clay crucibles, iron beads which ooze out from the blooms in the blast furnace. Bloom iron from Palghat is readily malleable, and furnishes a hard steel-like iron. It is necessary to subject the bloom to a second fusion and much hammering before they can bring it to the state of the soft malleable iron in which it is met with as an article of commerce.
The iron-ores of Coimbatore are of very fine quality, particularly rich in the metal, and highly magnetic.
Dr. Heyne, describing the manufacture of iron in the Karnatic to the south of the Pennar river, says, when first smelted, it is extremely brittle, requiring several operations to bring it into a malleable state. There are two varieties of ore used in the district in which he observed the processes. The one, an iron-sand, collected in the beds of rivers, consists of the protoxide, mixed with much of the peroxide ; the other, a red schist, is almost entirely composed of red oxide, but in the centre of the mass .it affects the magnet.
The woods used in Southern India for making charcoal for the iron works at Beypur were the vella - marda, karra - marda, Indian - gooseberry, Poohutn, nix vomica, and cassia. .
Iron-glance of the hills of Cupputral, in the Ceded Districts, furnishes an excellent malleable iron. Specular iron-ore occurs in the Sandur hills, about 30 miles W. from Bellary.
The Bellary district yields a variety of iron ores, some of them very rich in the metal, and several of them are associated with manganese.
The prevailing ores of iron of this district are the black and grey ores alternating with sandstone, liver-coloured ore (which has been repeatedly sent to Madras as copper-ore), and red jaspery clay iron-stones. They are also associated in the same district, and in the vicinity of Kurnool and Ghooty, with magnesian limestone, grits, con glomerates, aluminous shale, fireclay, and black dolomite.
The principal ores of the Cuddapah district are red, brown, and purple in colour, which yield iron of excellent quality and very malleable. Some of the magnetic iron-ores of the same district are particularly rich in iron, and a few of them contain traces of manganese. Of those from Chemur and Pulevendalah, the latter is magnetic, although earthy and dull red in the fracture, and bright red in the streak. The steel-grey and granular iron-ores of Chitwail, Camalapur, and Gurumcondah are all rich in the metal, and more or less magnetic. The yellow ochre and rusty ores of the Muddenpully taluk are said to yield good malleable iron. The steel-grey iron-sand Comarole and Yandapully in the Doopaud taluk are highly magnetic, and contain a little man ganese. The micaceous iron-ore and iron-glance of the Doopaud taluk are also rich in the metal.
Gunnygull hill ridge, south of Kurnool, is seamed with great veins of very pure specular iron-ore. A great cone-like mass of almost pure specular iron-ore rises out of the base of the northern slopes. Then S.E. of Ramulkota there is a ridge a 'perfect mine of iron ;' but the great local draw; back is the scarcity of fuel, of which only a small supply is obtainable from the low and thin jungle in the hilly regions to the southwards. Smelt ing is carried on at Ramulkota. The ore which is brought from an adjacent bill is massive, roughly granular, coarsely crystallized, and very brilliant. Usually the iron-ore is smelted once in a month, during 24 hours. The furnace is charged seven times during this day and night ; when seven lumps of smelted metal are obtained. The furnace is charged first (a fire being at the buttons) with powdered charcoal. Two large baskets (six or seven large Madras measures) of charcoal are thrown on the fire ; then a small basket of pounded ore (74 seers) and six small baskets of charcoal, that is, about 4 handful of iron and a hand ful of charcoal alternately, at about an interval of a minute. Nothing else is put in the furnace. The bellows are kept at work for about two or three hours. Then the soft mass of metal is raked out, beaten for a short time with heavy hammers until it assumes the rounded wedge-shaped form usually given to the lump of iron at native furnaces, a deep cut being made in the mass. This lump of metal is about three-quarters of the weight of pounded ore placed in the furnace, and it is worth three rupees. Afterwards it is reduced to bars of workable iron, by being heated four times in the forge, and beaten between each heating. The furnace is a small dome-shaped edifice, almost exactly like tho furnaces of the Salem district, both in shape and size.