308 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 1916. 



Metallurgical Society of America, January 12, 1915, which has been 

 already cited. The air passing through the furnace is, by volume, 

 nearly four-fifths inert nitrogen, which contributes nothing to the 

 reactions and is a serious absorber of heat. Were it possible to 

 relatively increase the proportion of oxygen, loss of heat might be 

 avoided and fuel consumption reduced. Mr. Johnson called atten- 

 tion to the production of greatly enriched proportions of oxygen 

 by the expansion of liquid air under suitable control, as now used in 

 practicable processes for obtaining oxygen on the one hand and 

 nitrogen on the other. Were it possible with the low-cost power, 

 to be developed by the products of the blast furnace, to manufacture 

 liquid air or to produce in the same general way a strongly enriched 

 oxygenated air for the intake, the volume of atmospheric gases 

 would be greatly reduced and the heat economies would ensue. The 

 contrast presented by employing the coldest substance known as a 

 means of facilitating one of the hottest reactions of technical prac- 

 tice is so novel as to arrest attention. Costs, however, should it ever 

 become practicable, place it in the remote future. 



A more immediately practicable economy, involving the saving of 

 waste, is the use of blast-furnace cinder for the manufacture of 

 cement. By just so much as this ordinarily rejected product can be 

 made a source of financial return, costs will be reduced. While we 

 ma}^ not realize the whimsical ideal presented by Mr. Johnson in 

 the above address, when he pictured the furnace of the future as 

 yielding pig iron at the tap and cement at the cinder notch, yet we 

 may think of slag utilization as helping to usher in the next age of 

 the world, the one which is rapidly displacing the present steel age — 

 the one which Ave all recognize as the inevitable age of cement. 



BIBLIOGRAPHY. 



1902. Andrew Carnegie. Rectorial Address, University of St. Andrews, Oct. 

 22, 1902, p. 36. 

 J. Stephen Jeans. Staffordshire Iron and Steel Institute, Dec. 13. 1902. 

 Iron and Coal Trades Review, vol. 65, pp. 1580. 1681. 



1905. R. A. Hadfield. Presidential Address in the Journal of the British Iron 



and Steel Institute, 1905. I, pp. 56-57, 59. 



N. S. Shaler. " The Exhaustion of the World's Metals," International 

 Quarterly, II, p. 230, 1905. 



Llewellyn Smith. A Blue Book of Iron Ore Deposits in Foreign Coun- 

 tries, compiled for the London Board of Trade, 1905. 



A. E. Tornebohm. *' The Iron Ore Supply of the World," Teknisk 

 Tidskrift, Sept., 1905. The Iron Age, Nov. 2, 1905, pp. 1158-1160. 



1906. E. C. Eckel. " A Review of Conditions in the American Iron Industry," 



Engineering Magazine, June, 1906, p. 521 ; U. S. Geological Survey, 

 Bulletin 2S5, pp. 172-179, 183-189, 1906. 

 C. K. Leith. " Iron Ore Reserves," Economic Geology, I, p. 360, 1906. 



