Aug. 31, 1888.] 



SCIENTIFIC NEWS. 



211 



steel, and its contraction is decidedly greater. It is 

 manufactured by any of the ordinary steel-making pro- 

 cesses, the basis, i.e., the material before the ferro-man- 

 ganese is added, being preferably decarbonised iron (prac- 

 tically pure iron, Fe) or mild steel. The ferro-manganese 

 is added in a molten state, or very highly heated. The 

 steel is then ready for casting into ingots or other forms. 

 It is most important that the carbon should be kept as 

 low as possible, especially in the 14 per cent, material, 

 where it should not exceed about 1 per cent, or the pro- 

 duct will be inferior. For this reason, the ferro- 

 manganese used should contain high percentages of 

 manganese, such as 80 to 84 per cent., now easily pro- 

 curable at as low a price as ^9 per ton. About 0^50 per 

 cent, of the manganese is oxidised — that is to say, to 

 obtain a steel with about 13 per cent, about 13! percent, 

 of manganese must be added. It will be readily under- 

 stood that the ordinary crucible steel-making process is 

 not suitable for the making of this manganese steel, on 

 account of the manganese cutting or slagging the pots. 

 He then proceeded to give a more exact description of 

 the qualities of the material. Referring to its peculiar 

 hardness, he said it was somewhat difficult to describe 

 this quality, because all the specimens are exceedingly 

 hard — in fact, it is scarcely possible to machine any of 

 them on a practical scale. Yet such hardness varies 

 considerably in degree, being most intense in the cast 

 material containing 5 to 6 per cent, of manganese which 

 no tool will face or touch. A slight decrease then occurs, 

 and the 10 per cent, material gives comparatively the 

 softest condition. Upon a further addition of manganese 

 an increase again takes place, and at 22 per cent, it is 

 very hard, though still not so much so as in the 5 per 

 cent, material. It was difficult to explain the cause of 

 this hardness, because manganese, when added to copper, 

 does not produce this remarkable change, and why, there- 

 fore, should manganese added to iron, which in its pure 

 state is but little harder than copper, produce such a hard 

 alloy ? Apparently iron must have some property of 

 changing its form in a way not yet understood. As 

 bearing upon this point, a well-known metallurgist, Mr. 

 John Parry, of Ebbw Vale, said in an article on " Spec- 

 troscopic Analysis of Iron and Steel," that in his opinion 

 the search for and determination of substances technically 

 termed impurities in iron and steel is nearly over ; we 

 have little left for research except the iron itself. It was 

 possible therefore that in this direction a clue might be 

 furnished to many as yet unresolved problems, and 

 possibly in the manganese steel there is some change in 

 form of the iron itself. ■ Manganese steel, notwithstanding 

 its high proportion of metallic iron — the most magnetic 

 metal known — possesses the peculiar property of being 

 almost entirely non-magnetic. Rinmann, as far back ag 

 1773, noticed that manganese alloys gave non-magnetic 

 material. This was also noticed by Mr. David Mushet 

 about 1830. This Dr. Hopkinson suggested that the man- 

 genese in the steel was not merely mixed mechanically 

 with the iron, but that it entered into the molecule in 

 such a way as to destroy its magnetic properties, which 

 are the samein either its cast or forged, hard or toughened 

 state. Another peculiar physical characteristic of man- 

 ganesesteel noticed by Professor Barrett was as follows : — 

 Some years ago he discovered that when iron or steel 

 heated to whiteness was allowed to cool in a dark room, 

 the moment the temperature of the steel reached obscurity 

 a sudden revival of temperature occurred, an outward 

 rush of heat taking place, and the steel glowing again 



red hot. This afterglow or recalescence, which occurred 

 in all ordinary steel, did not take place with this material, 

 as was the case in other non-magnetic metals, such as 

 platinum, silver, copper, etc. In some recent experi- 

 ments it had been noticed that drillings of 20, 30, and 36 

 per cent, manganese steel, which were practically un- 

 attracted by the magnet, after being heated to redness 

 and allowed to cool, exhibited a considerable increase 

 in magnetic susceptibility. This occurred even when 

 the drillings were heated and cooled in hydrogen. The 

 fact stated could scarcely be due to oxidisation of the man- 

 ganese owing to heat, because the weight before and 

 after the experiments was the same. In conclusion, he 

 said it was not possible within the scope of a paper to 

 deal with the many interesting points raised by the 

 peculiar qualities of manganese steel. His hope in 

 bringing this matter before the Iron and Steel Institute 

 was as stated by Mr. Howson, when addressing the Cleve- 

 land Institute of Engineers last year : " Individual effort, 

 although exerted in the most useful direction, is often ot 

 but small account when taken alone. It is only when 

 submitted to the scrutiny of many minds, and freely dis- 

 cussed, that it proves of real value." He hoped it might 

 be so in the present instance. 



In the course of the discussion, M. Gautier described ex- 

 periments made in France in the application to practical 

 uses of manganese steel. The first application, he said, 

 was in the direction of making horse-shoes. The alloy 

 contained 12 per cent, of manganese. But a difficulty 

 was found in the fact that if nails of the same material 

 as the shoe were used for fastening on the shoes, no 

 file could be found of sufficient hardness to operate 

 upon them. Nails, however, of ordinary steel were 

 used without any practical disadvantage, when the heads 

 were embedded below the surface of the harder metal. 

 Experiments on a large scale were being made with 

 some regiments of French cavalry. Some success had 

 attended the casting of wheels of manganese steel for 

 small mining cars. The difficulty they found was to 

 withdraw the castings rapidly enough out of the moulds, 

 because, as stated in the paper, the manganese steel was 

 much improved by softening in water. It was a curious 

 fact that that which was a hardening process for other 

 metals was a softening process for manganese alloyed 

 with iron. The difficulty was to put it into the water 

 quickly enough and at the proper temperature ; the cast 

 wheels when extracted from the moulds shrinking, if 

 the extraction was not done rapidly. To overcome this 

 was, however, a question of practice. Then experi- 

 ments were being made in the manufacture of armour 

 plates. The difficulty here was the management of 

 heavy weights of the steel. They found also that the 

 manganese steel which they made contained too large a 

 percentage of carbon, and some cracking occurred when 

 the plates were dipped into water. They would, he 

 believed, soon be able to manufacture a better quality of 

 steel, which would resist the impact of the shells. The 

 shell was broken, but the plate also was broken and 

 cracked, and two or three shots brought it down. He 

 should be glad at the next meeting of the Institute to give 

 more information on this practical question. 



In the afternoon a visit was made to Leith Harbour 

 and Docks, down the north sides of the Albert and Edin- 

 burgh Docks, round the east end, and up the south, to 

 North Leith Station, where the train for Edinburgh was 

 joined. 



On the 22nd, the first paper read was on " The Forth 



