39 o METALLURGY 



carbon dioxide. Burrell and Seibert (id.-, Technical Paper 13, 1911) find that oxygen is 

 absorbed by the coal in mines. Samples of gases collected by the same authors near a 

 fire, where the coal was intensely hot and the oxygen content of the mine atmosphere 

 was only 2 per cent contained 1.5 per cent of CO. 



Our knowledge of the composition of " blackdamp " has been greatly extended by 

 the researches of Haldane. In a paper on " A Flame-Test for the estimation of Oxygen 

 and Blackdamp in Naked Light Mines " (Trans. Inst. Min. Eng., Vol. 41, p ; 455), he 

 describes a series of laboratory experiments with an apparatus consisting of a glass tube 

 and thin tapers. When a lighted taper is held inside the tube, the flame is extinguished 

 by the draught so produced at a point lower down or higher up the tube, according to 

 the percentage of oxygen. The tube is graduated to indicate various percentages of 

 oxygen and blackdamp. 



R. Nowicki (Oesterreichische Zeitschrift fur Berg-und Huttenwesen, 1911, p. 587) 

 describes an apparatus for detecting CO, using palladium chloride. Many, however, 

 prefer the use of animals to chemical tests, and G. A. Burrell (U.S. Bur. Mines Tech., 

 Paper n, 1912) gives a preference to canaries as against mice. 



(ALLAN GREENWELL; HUBERT GRF.ENWELL.) 



METALLURGY 



The period 1909-12 has not been marked by any great or revolutionary development 

 in either metallurgical science or practice; or rather, if any of the developments which 

 have taken place should be destined to carry important changes in their train, no strik- 

 ing signs of such changes have as yet become visible. In general terms progress here, 

 as in most industries, has been in the direction of increased production, increased econ- 

 omy of labour, and more efficient utilisation of raw materials and of by-products, and 

 in some cases this has led to the installation of plant on an astonishingly large scale. In 

 other directions, the systematic and scientific exploration of the available materials and 

 their products has led to the evolution of new and valuable materials, principally in the 

 form of novel alloys. The developments of metallurgical practice in reference to the 

 several groups of metals may be more conveniently considered before dealing with the 

 scientific aspects of metallurgy in general. 



Iron and Steel (E. B. xiv, 801 el seq.). Ore resources are being further developed, 

 and the beginnings of iron and steel industries have been made both in South America 

 and Australia. Progress has also been made in the utilisation of finely divided ores and 

 such materials as blast-furnace flue-dust by improved methods of briquetting; in the 

 Schumacher process the addition of a small percentage of magnesium chloride solution 

 to the flue-dust serves to release a latent power of setting, .while in the Dwight-Lloyd 

 system the material is sintered by mixing it with finely-divided carbon which is caused 

 to burn, thus partially reducing the ore and producing a porous sintered mass. 



In blast-furnace practice, the use of thin-lined and water-cooled furnaces has in- 

 creased, while the drying of the blast is becoming universal. For this purpose several 

 new methods have been used, including refrigeration by the use of ammonia without 

 the intervention of brine, and the use of calcium chloride as a drying agent. The latter 

 is used for six or eight hours and is then regenerated by drying in the heat of the flue- 

 gases. The former process has been used in Wales and the latter in Luxemburg, while 

 at one Belgian plant the use of blast enriched with oxygen has been tried, and if the price 

 of oxygen can be further reduced this may prove to be an important improvement. In 

 this connection the use of an oxy-acetylene torch for burning out tapping holes may also 

 be mentioned. The utilisation of blast-furnace gases has been pushed further, so that 

 these furnaces now constitute important sources of power; the use of the gas in open- 

 hearth furnaces has been contemplated, but its calorific value is too low to allow of its 

 use alone. Mixed with producer gas or with gas from coke-ovens, however, success has 

 been attained. Quite recently the utilisation of the waste heat of blast-furnace slag has 

 been accomplished by running the molten slag into water and allowing it to generate 

 steam for driving turbine engines. 



