president's address — SECTION B. 107 



excess of air during the copper-forming period, which would be taken 

 high at an average of 5.8 per cent, of air by volume, give a final tempera- 

 ture of 1,173°, and, for no excess of air, of 1,223°. The initial tempera- 

 ture assumed for the white metal is, however, much too low, and the 

 actual figure would appreciably increase the final heat. Yet, even as- 

 they stand, these results more nearly approach the truth than any 

 other calculated results given in the literature of the subject. By 

 means of the optical pyrometer of Mesne and Nouel, controlled by 

 Le Chatelier's thermo- electrical pyrometer, Jannettaz ascertained 

 the temperature for 30 per cent, matte in the selecteur, at the beginning 

 of the blow, as 1,016°, during the blow as 1,260°, and at the end as 

 1,200°. Under Professor H. M. Howe's direction the temperatures 

 were similarly measured, in a small upright converter of early type, as 

 rising from 1,234° to 1,393° during the first blow, and as standing at 

 from 1,220° to 1,239° in the after-blow. A repeat test gave the figures 

 as 1,090° to 1,305°, and 1,192° to 1,164° respectively. It is obvious, 

 from the paucity of data, how the subject has been neglected, though 

 it is one of the most interesting in all modern metallurgy. Incidentally, 

 the results confirm the inference logically to be dr?wn from the chemical 

 featiires, that while there is a rise of heat in the slagging period there 

 is a gradual fall of temperature in the copper-forming period — a circum- 

 stance which occasionally demands special attention in actual work, 

 and is remedied by throwing in a small amount of carbonaceous material 

 or ordinary matte. Finally, it may be remarked that tests with small 

 laboratory converters have established temperatures, when using 

 ordinary air, of 1,240° to 1,280° for the slagging period and of 1,170°^ 

 to 1,200° for the copper period. 



Use of Oxygen Gas.— It need scarcely be remarked that it has 

 long been suggested to use oxygen gas, or air enriched with oxygen, 

 nor that the only obstacle up to date has been the cost. The problem 

 of the cheap production of the gas on an industrial scale, suiting metal- 

 lurgical rec|uirements, is, however, daily drawing nearer solution, and 

 the regular application of oxgyen gas in this and numerous other 

 branches of the smelting art is only a question of time. So far, only 

 laborator}' experiments (6) have been made in the Bessemerising of 

 copper and nickel mattes. They have indicated most striking improve- 

 ments. Even slight enrichments of the oxygen in the atmosphere, 

 not exceeding an increase from 25 per cent, to 29 per cent, by volilme, 

 have given splendid results. The temperatures were throughout 

 increased by from 100° to 200°, and the velocity of the reactions was 

 so accelerated that the same work could be done in two-thirds to one- 

 half of the usual time. Further effects were a smaller volume of waste 

 gases, and higher contents of same in sulphurous acid, the percentage 

 being nearly doubled for air enriched to the slight extent mentioned. 

 Practical consequences are that a given converter plant will be enabled 

 to double its capacity, and the gases will be rendered more suitable 

 for acid-making than they now are, owing to the difficulty of pre- 

 venting dilution with outside air. It is reckoned, on general data, 

 (6) Brandt, Metallurgie, vol. II, 1905 ; Hesse, ibid., vol. III., 1906. 



