Mav 14, 1 896 J 



NA TURE 



39 



The following list of papers to be read and discussed was on 

 the agenda. 



" On the Rate of Diftusion of Carbon in Iron," by Prof. 

 W. C. Roberts- Austen, C.B., F.R.S. 



" On some Alloys with Iron Carbides," by J. .S. de Benne- 

 ville, of Philadelphia. 



"On Mond Gas as applied to Steel Making," by John H. 

 Darby, of Brymbo, North Wales. 



" On Hot Blast Stoves," by B. J. Hall, of Westminster. 



" On the Hardening of Steel," by H. M. Howe, of Boston, 

 U.S. 



" On the Introduction of Standard Methods of Analysis," by 

 Baron Hans Jiiptner von Jonstorff, of Neuberg, Austria. 



" On the Production of Metallic Bars of any Section by Ex- 

 trusion," by Perry F. Nur.sey, London. 



"On Mr. Howe's Researches on the Hardening of .Steel," 

 by F. Osmond, of Paris. 



" On the Treatment of Magnetic Iron Sand," by E. Metcalf 

 Smith, of New Zealand. 



" On the Making of the Middle Lias Ironstone of the Mid- 

 lands, ' by E. A. Walford, Banbury. 



Mr. Hall's paper was first taken. It described a form of 

 hot blast stove which has now been in use many years, the 

 first, we believe, having been erected about twelve years ago. 

 It is known as the Ford and Moncure stove, and is of fire-brick, 

 having the ordinarj' chequer work, although the arrangement 

 varies somewhat from the Cowper or Whitwell patterns, the 

 chief difference being that the stove is divided by walls into 

 four parts. The object is to give facilities for clearing from 

 dust. When the change is made from gas to air the whole of 

 the blast is passed through one of the four divisions, naturally 

 in a verj' concentrated form. This blows the dust out of the 

 chimney-top, or deposits it in the flues, from whence it can be 

 removed at convenient times. Details given by the author 

 showed that the stoves have a long life, a fact which is per- 

 haps as much due to the excellent proportion on which they 

 are designed as to any special novelty in the construction. 

 From what was said during the discussion, it would appear that 

 the dust-removing device answers satisfactorily. 



The next paper taken was Mr. Nursey's contribution, which 

 described a very interesting departure in the production of metal 

 bars of various sections. 



The author stated that the system of manufacture was the 

 invention of Mr. Alexander Dick, the inventor of Delta metal. 

 It related to the production of all kinds of metallic sections, 

 from thin wire or plain bars to complex designs, by simply 

 forcing metal, heated to plasticity, through a die by hydraulic 

 pressure. He referred to the fact that although the principle of 

 extrusion was employed in the manufacture of lead pipe and 

 lead wire, yet the temperature was very much lower than in 

 Mr. Dick's system, which required the metal to be red-hot, or about 

 1000° F. The process consisted in placing the red-hot metal in 

 a cylindrical pressure chamber, or container, at one end of 

 which is a die. Upon pressure being applied at the opposite end 

 the plastic metal is forced through the die, issuing therefrom in 

 the form of rods or bars of the required section and length. 

 The container of the first apparatus made was a solid steel 

 cylinder, bored out to the required diameter to form the chamber 

 for the hot metal, and heated in a coke fire. In practice, 

 however, it W'as found that the strain set up by the unequal 

 expansion and contraction of the walls of the cylinder, added 

 to that caused by the internal pressure applied to force the 

 metal through the die, developed cracks in the cylinder which 

 rendered it useless. After a long series of experiments with 

 various kinds of steel cylinders, Mr. Dick abandoned the solid 

 wall principle and devised a built-u]) container. It is composed 

 of a series of steel tubes of different diameters, placed one out- 

 side the other, with annular spaces between them, these spaces 

 being filled with a dense non-conducting packing. This device 

 proved perfectly successful, and machines on this principle are 

 now in operation on a commercial scale at the works of the 

 Delta Metal Co., in Germany, and at one of the large Midland 

 metal rolling mills. These machines aie served by two men 

 and one boy, so that the cost of labciir per ton is very small. 

 The author described the working of the system, and referred to 

 the great variety of sections, some of a very complex nature, 

 produced in Delta metal, brass, aluminium, aluminium bronze, 

 and other alloys and metals, samples of which were exhibitetl 

 on the table of the theatre. They ranged from wire weighing 

 about I ICO of a pound per foot run, t'l !:eavy rounds, squares. 



NO. 1385. VOL. 54] 



and hexagons weighing 40 lb. and over per foot run. Among 

 the examples was a complex moulding that could not possibly 

 have been made by rolling in the usual way followed for making 

 metal articles of this nature. Mr. Nursey pointed out that the 

 pressure put upon the metal greatly increased its strength, and at 

 the same time rendered it still more homogeneous. Some tests 

 made at Woolwich Arsenal with Delta metal bars produced by 

 extrusion showed a tensile strength of 48 tons per square inch 

 with 32-5 per cent, elongation on 2 inches, as against 38 tons 

 per square inch tensile strength and 20 per cent, elongation of 

 rolled bars of the same metal. The author concluded by stating 

 that Mr. Dick was engaged on experiments with the view of 

 producing sections in iron and steel similar to those at present 

 turned out in Delta metal. 



In the discussion which followed the reading of Mr Nursey's 

 paper, Mr. Snelus described a process of covering telephone 

 cable with lead, somewhat analogous to that referred to by the 

 author. This cable contained over 150 wires, and was three 

 inches in diameter. The fluid lead was pressed over it through 

 dies. The great difficulty in all processes of formation by 

 extrusion is to get a inaterial for making the dies which will 

 stand the hard usage to which they are put. Mr. Dick uses 

 tungsten steel, a very hard material which does not require 

 tempering : this, it seems, is good enough for Delta metal, one of 

 the many new bronzes, and for the other materials mentioned. But 

 if it were necessary to deal with metals having a higher melting 

 point, a still more refractory metal would be required, and one 

 of equal hardness, as the dies must not only withstand heat, but 

 erosion. Mr. Snelus was of opinion that if the container, or 

 cylinder, used for forcing out the fluid metal, were made of some 

 highly refractory earth, that steel pipes could be made in this 

 way. That, of course, would be a great commercial success, 

 for not only could the pipes be cheaply manufactured in long 

 lengths, but the quality would doubtless be much improved. 

 In the present day of water-tube boilers this is a matter well 

 worth considering. The difficulty in making steel tubes, how- 

 ever, does not appear to rest with the production of a refractory 

 container. Mr. Dick said that he had made steel bars by 

 extrusion, although it was done accidentally, and the trouble 

 was, not that the cylinder gave way, but that the dies would 

 not stand the work ; if, therefore, an ingenious metallurgist can 

 discover an alloy as hard as tungsten steel, and more refractory, 

 he will possibly make a considerable fortune. 



Mr. Metcalf Smith's paper was next taken. The author 

 described the method adopted in New Zealand of smelting, or 

 perhaps one should say melting, the iron .sand found so largely 

 in that country. The paper stated that the sea cliffs on this part 

 of the coast consist of a combination of silica sand and a rich 

 magnetic iron sand ; the gradual crumbling of these cliffs, 

 together with large quantities of iron sand brought down by the 

 rivers and streams, draining the slopes of Mount Egmont, result 

 in a deposit of almost pure iron sand on the beach, a large pro- 

 portion of the lighter silica sand being washed out to sea. 

 Excavations have been made on the beach showing a depth of 

 iron sand of fourteen feet, whilst the same material has been 

 dredged up at a distance of three miles out to sea. Nature 

 seems to have devised this district most fitly for an iron industry ; 

 for not only are these vast deposits of magnetic iron so easily 

 obtainable, but in close proximity there are extensive coal 

 beds. There is also limestone containing SS per cent, of calcium 

 carbonate, timber for charcoal if required, and, indeed, provision 

 for supplying all the needs of iron manufacture. liere is an 

 analysis of the iron sand, made by Sir James Hector : 



Peroxide of iron 1 

 Protoxide of iron J 

 Oxide of titanium ... ... ... ■■ S'o 



Silica S-o 



Water and loss 20 



Of course iron sand is known in other countries besides New 

 Zealand, and efforts have often been made to smelt it. The 

 difticulty, however, l)as been that it comes down and chokes the 

 furnace when melting begins, so that it descends to the hearth 

 unreduced. This is got over in New Zealand by kneading it 

 into bricks with clay, which is found close by. In this way hard 

 and compact lumps are procured, which will stand the pressure 

 and grinding action in travelling through the furnace. One ton 

 12 cwt. of iron sand is mixed with lo cwt. of clay ; and in this 



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