374 SCIENCE PROGRESS 



Professor Louis's report on the British iron field is, therefore, of 

 special interest, particularly as he takes a very pleasing view 

 of the extent of our reserves. The British output of pig-iron is 

 now over fifteeen million tons per annum and there is still, 

 on the whole, a slight annual increase in the amount produced. 

 Professor Louis concludes that the British Isles have in reserve 

 39,500 million tons, containing an average of from 30 to 35 per 

 cent, of iron. If all this ore could be used, it would supply all 

 our blast furnaces for nearly 3,000 years. Professor Louis, of 

 course, recognises that a very large proportion of the ores 

 cannot be smelted profitably under any conditions that may be 

 reasonably expected, though it may be added that he has formed 

 a much more favourable view of the. extent of the Wealden ores 

 than I formed after some inquiry into their quantity in 1907. 



Dr. Sjogren has divided the world into sections A — D, 

 according to the extent to which available estimates can be 

 trusted. In division A, which includes 13*3 per cent, of the 

 land of the world, the calculations are fairly trustworthy. 

 In division B, including io'3 per cent, of the land, only very 

 approximate estimates can be made. In division C, including 

 51*6 per cent, of the land, no numerical estimates are possible. 

 Division D includes the unknown countries and the Polar 

 regions, covering 24*8 per cent, of the land area. Hence even 

 general estimates of the iron-ore supplies are possible for 

 less than a quarter of the land of the world. Professor 

 Sjogren has recently proposed a formula which appears to 

 yield the most probable approximation to the ore in the less- 

 known countries. He takes the average iron-ore content per 

 square mile of the lands in division A and multiplies this 

 factor by the remaining land area; according to this method, 

 the iron-ore supply in it is some 425,000 million tons. This 

 cheering estimate may be exaggerated if Europe and the eastern 

 states of America, by some fortunate circumstance, have been 

 endowed with more than the average share of iron ; and as 

 the iron-ores were only discovered after the settlement of 

 those countries, it seems probable that the extent of the ore 

 supplies is due to the thoroughness with which search has been 

 made for them. 



No doubt in some cases fuller knowledge may involve a 

 a reduction in the estimated quantities. Vague reports and 

 traditions of mountains of iron ore may prove to be exaggerated; 



