Dr. F. H. Hatch — Iron-ores of the United Kingdom. 391 



purification of illuminating gas. In the Kent coalfield a bed of 

 oolitic ironstone, 16 feet thick, has been cut in the shaft of the 

 Dover Colliery at a depth of 593 feet from the surface. This 

 stone contains, as mined, 33 per cent of iron, 15 per cent of silica, 

 9 per cent of lime, 0*45 per cent of phosphorus, and 005 per cent of 

 sulphur. With regard to mechanical condition, it is rather friable 

 and may have to be sintered or briquetted before use in the blast- 

 furnace. On account of its favourable situation in a coalfield and 

 on the seaboard it is most probable that steps will be taken to work 

 this deposit in the near future. 



The other Jurassic ironstones are all worked, and in 1917 accounted 

 for over 80 per cent of the total output of iron-ore in the United 

 Kingdom, the remaining 20 per cent being made up of Haematite, 

 mined in Cumberland and Lancashire (10J per cent) ; Blackband 

 and Clay-ironstone, mined in the English and Scotch coalfields 

 (8 per cent) ; and sundry ores mined in Wales, Forest of Dean, 

 Devonshire, Weardale, and Ireland (l-§ per cent). 



Table showing relative production of different classes of 

 British Iron-ores. 



Jurassic ironstones .... 

 West coast (Hsematite ore) . 

 Blackband and Clay-ironstone in coalfields 

 Sundry ores 



80-0 



10-5 



8-0 



1-5 



100-0 



Taking the Jurassic ironstones in descending order the proportion 

 in which they were worked (in relation to the total production of the 

 United Kingdom) in 1917, and their iron-content, are as shown in 

 the table : — 



Table showing relative Production and Iron-content of the 

 Jurassic Ironstones. 



Ironstone. 



Inferior Oolite (Northampton and 

 Rutland) . . . . . 



Middle Lias (Cleveland) . 



Middle Lias (South Lincolnshire, 

 Leicestershire, and Oxfordshire) . 



Middle Lias (Raasay) 



Lower Lias (North Lincolnshire) . 



Ratio to 

 Total Production. 



% 



21 

 32 



9 

 0-5 



18 



Average Iron 



Content 

 (as mined). 



% 



32 



28 



25 

 23 

 23 



27-6 



The average composition of the different Jurassic ironstones is 

 shown in the following table : — 



