TRANSACTIONS OF SECTION E. 653 



developments even within the last two or three years have made the district one of 

 the richest in the kingdom with regard to coal supply. The clay ironstone, ferrous 

 carbonate with clay, yields an excellent pig iron, containing about 06 per cent, 

 phosphorus, and suitable for making into castings and for the manufacture of the 

 best qualities of wrought iron for use as such. This ore is the source of the famous 

 Yorkshire iron, still made near Leeds, though in diminishing quantities. The great 

 bulk of the ironstone now used is the cheaper variety from Northampton, Leicester, 

 and Lincoln, and consists of brown iron ore, hydrated ferric oxide, yielding pig 

 irons containing about 1\ per cent, of phosphorus. These are suitable for manufac- 

 turing cast-iron castings and ordinary wrought iron and for making into basic 

 steel, the refractory dolomite necessary for lining the vessel or making the hearth 

 in which the steel is made being procured from the magnesian limestone to the 

 east. These pig irons are not suitable for making into the highest qualities of 

 Sheffield's special steels, so hematite pig-irons, from the hematite ores of Lanca- 

 shire, Cumberland, and Spain, are imported for making into acid Bessemer or 

 acid open-hearth steel, that is, steel made in an acid- or silica-lined vessel or 

 hearth, and that can thus be finished in contact with an acid slag. The best 

 qualities of Swedish wrought irons are also imported for making into cutlery, 

 edge tools, general cutting tools for engineers, &c. As refractory materials for 

 these processes, and even for the roofs of the basic furnaces, much acid material 

 of great purity is required. Some of the Coal Measure sandstones consist of 

 particles of quartz that have been cemented by silica, so that the whole rock very 

 often consists of 98 per cent. Si0 2 . This rock, called ganister, is mined round 

 Oughtibridge and made into refractory silica bricks for withstanding the highest 

 furnace temperatures. A similar firestone is used for building the walls between 

 the crucible holes and for other purposes, and ground ganister, mixed with a little 

 fireclay and water, is rammed round wooden moulds to form the crucible melting 

 holes and also the linings of Bessemer converters. Fireclay is also abundant, 

 providing the firebricks used for the less highly tried portions of the furnaces. 

 Some of the carboniferous sandstones yield splendid grindstones, and building 

 stones are abundant and at high levels, whilst there are deposits that are of the 

 composition necessary for making ordinary bricks without any additions. The 

 inexhaustible Derbyshire limestone is available as a flux, and the fact that 

 lead mining in the mountain limestone was once a great industry has an 

 important bearing on the manufacture of basic steel, for the great heaps of 

 gangue left by the miners are being worked over for fluorspar, which is used to 

 help in desulphurising the metal. Barytes is won at the same time, and though 

 mainly used as the most permanent white basis of photographic papers and for 

 mixing with white lead, some of it may be converted into BaCI,, which is brought 

 to high temperatures by electrical means for heating high-speed steels for 

 gardening purposes. The millstone grit, once so famous for its use as millstones 

 for grinding corn and for erecting buildings to last for aye, is now superseded, for 

 the former by iron rolls, and as it is too hard to work for present-day building 

 requirements, it is mainly left to look grim and grand in the scenery, though 

 recently it has been much used in building the new great dams and helping to add 

 the only feature our beautiful district lacked, extensive sheets of water. Ganister 

 has been mentioned, a sandstone in which the particles of quartz are cemented by 

 quartz. To the east of Sheffield, in the Upper Permian and perhaps Lower Triassic 

 beds, as, for example, near Worksop, there are extensive deposits of a natural red 

 moulding-sand of the best quality, in which each Tounded particle of quartz is 

 roughened by a coating of reddish brown oxide of iron, and the whole deposit 

 contains the right admixture of clay to give the necessary compromise between 

 binding quality on the one hand and porosity on the other required in a moulding 

 sand for general foundry-work. 



Sheffield is therefore situated in the midst of an abundance of flux for dealing 

 with impurities, of fuel for power and for attaining the high temperatures required 

 in the manufacture of iron and steel, and of the best of refractory materials for 

 withstanding these high temperatures ; and when materials at hand do not 

 satisfy the severe requirements of the special trades others are freely imported, 

 as in the case of hematite pig-irons and Swedish and other wrought irons for 

 making into the highest qualities of special steels. 



1910. V V 



