. Fig. I.—hessi,e Output of chalk, with two diggers operated by five men iu all, totals 5,000 to 6,000 tons per week. to a powder so fine that, in order to qualify- for the British Standard specification, 86 per cent, of it must pass a sieve with 32,400 meshes to the square inch. In this state it is the finished Portland cement. At Barton the cement is ground so that approximately 97 per cent- passes this sieve. The whole process is, at the present day, carried out in the most scientific manner ; several chemists are employed in a large establishment. This ensures the product being n
. Fig. I.—hessi,e Output of chalk, with two diggers operated by five men iu all, totals 5,000 to 6,000 tons per week. to a powder so fine that, in order to qualify- for the British Standard specification, 86 per cent, of it must pass a sieve with 32,400 meshes to the square inch. In this state it is the finished Portland cement. At Barton the cement is ground so that approximately 97 per cent- passes this sieve. The whole process is, at the present day, carried out in the most scientific manner ; several chemists are employed in a large establishment. This ensures the product being not only good, but invariably good. In the old days, when the manufacture was carried out by rule of thumb, the resulting cement was very unreliable. The silica and alumina in the clay combine with the lime in the chalk. The compound of the greatest cementitious establishment and have enormously increased the use of all kinds of work in reinforced concrete, such as bridges, retaining-weUs, reservoirs, factories, warehouses, floors, and such things as seats, sign-posts, signal-posts, which it is now becoming very common to make of this material. The Humber-side possesses all the natural advantages for manufacturing a first-rate Portland cement. The calcium carbonate is there on both sides of the river, in cliffs, some 200 to 300 ft. high, which constitute the high ground laiown as the Lincolnsliire and Yorkshire Wolds. They contain some of the largest chalk-quarries in the country. The necessary clay lies at the foot of these cliffs in the form of river-mud, probably deposited
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