September 4, 1S90J 



NATURE 



439 



projectiles necessitates their being produced hollow ; their 

 cavities or chambers are only of small capacity, but the charge 

 of violent explosive which they can contain, and which can be 

 set into action without the intervention of fuze or detonating 

 appliance, suffices to tear these formidable punching-tools into 

 fragments as they force their way irresistibly through the 

 armoured side of a ship, and to violently project those frag- 

 ments in all directions, with fearfully destructive effects. The 

 employment of chromium as a constituent of steel plates used for 

 the protection of ships of war is already being entered upon, 

 and the influence exerted by the presence of that metal in small 

 quantities in steel employed in the construction of guns is also 

 at present a subject of investigation. At Crewe, Mr. F. Webb 

 has for some time past used chromium, with considerable 

 advantage, in the production of high-quality steels for railway 

 requirements. 



The practical results attained by the introduction of copper 

 and of nickel as components of steel have also recently attracted 

 much attention. At the celebrated French steel works of M. 

 Schneider, at Creuzot, the addition of a small percentage of 

 copper to steel used for armour-plates and projectiles is practised, 

 with the object of imparting hardness to the metal without pre- 

 judice to its toughness. James Riley has found that the presence 

 of aluminium in very small quantities facilitates the union of 

 steel with a small proportion of copper, and that the latter in- 

 creases the strength but does not improve the working qualities 

 of steel. With nickel, Riley has obtained products analogous 

 in many important respects to manganese steel ; the remarkable 

 differences in the physical properties of the manganese alloys, 

 according to their richness in that metal, are also shared by the 

 nickel alloys, some of these being possessed of very valuable 

 properties ; thus, it has been shown by Riley that a particular 

 variety of nickel-steel presents to the engineer the means of 

 nearly doubling boiler pressures, without increasing weight or 

 dimensions. He has, moreover, found the coexistence of 

 manganese in small quantity with nickel in the alloy to con- 

 tribute importantly to the development of valuable physical 

 properties. 



The careful study of the alloys of aluminium, chromium, 

 manganese, tungsten, copper, and nickel, with iron and with 

 steel, so far as it has been carried, with especial reference to the 

 influence which they respectively exercise upon the salient 

 physical properties of those materials, even when present in 

 them in only very small proportions, has demonstrated the im- 

 portance of a more searching or complete application of chemical 

 analysis, than hitherto practised, to the determination of the 

 composition of the varieties of steel which practical experience 

 has shown to be peculiarly adapted to particular uses. It appears, 

 indeed, not improbable that certain properties of these, which 

 have been ascribed to slight variations in the proportion or the 

 condition of the constituent carbon, or in the amounts of silicium, 



fhosphorus, and manganese which they contain, may sometimes 

 ave been due to the presence in minute quantities of one or 

 other of such metals as those named, and to the effects which 

 they produce, either directly, or indirectly by modifying or 

 counteracting the effects of the normal constituents of steel. The 

 important part now played by manganese in steel manufacture is 

 an illustration of the comparatively recent results of research, 

 and of practical work based on research, in these directions, and 

 the effects of the presence in steel of only very small quantities 

 of some of the other metals named are already, as 1 have pointed 

 out, being similarly understood and utilized. 



Such systematic researches as those upon which Osmond, 

 Roberts- Austen, and many other workers have been for some 

 time past engaged, may make us acquainted with the laws which 

 govern the modifications effected in the physical characteristics 

 of metals by alloying these with small proportions of other 

 metals. The suggestion of Roberts-Austen, that such modifica- 

 tions may have direct connection with the periodic law of Men- 

 deleeff, which may furnish explanations of the causes of specific 

 variations in the properties of iron and steel, has been followed 

 up energetically by Osmond, who has experimentally investi- 

 gated the thermal influence upon iron of the elements phosphorus, 

 sulphur, arsenic, boron, silicium, nickel, manganese, chromium, 

 copper, and tungsten. He regards his results as being quite 

 confirmatory of the soundness of Roberts-Austen's suggestion, as 

 they demonstrate that foreign elements having atomic volumes 

 lower than iron tend to make it assume or preserve the particular 

 molecular form in which it has itself the lowest atomic volume, 

 while the converse is the case for the foreign elements of high 



NO. 1088, VOL. 42] 



atomic volume. An analogous influence was found to be exerted by 

 those two groups of elements upon the permanent magnetization 

 of steel. 



Captivating as such deductions are, those who have devoted 

 much attention to the practical investigation of iron, steel, and 

 other metals, cannot but feel that much caution has to be 

 exercised in drawing broad conclusions from the results of such 

 researches as these. Like the investigations recently made with 

 the object of ascertaining the condition in which carbon exists in 

 steel, and the part played by it in determining the modifications 

 in the properties developed in that material by the influence of 

 temperature and of work done upon it, they are surrounded by 

 formidable difficulties, arising from the practical impossibility 

 of altogether eliminating the disturbing influences of minute 

 quantities of foreign elementary bodies, co existing in the metal 

 operated upon, with those whose effects we desire to study. 

 Certain it is, however, that by acquiring an accurate acquaintance 

 with the composition of varieties of iron and steel exhibiting 

 characteristic properties ; by persevering in the all-important 

 work of systematic practical examination of the mechanical and 

 physical peculiarities developed in iron and steel of known com- 

 position by their association with one or more of the rarer metals 

 in varied proportions, and by the further prosecution of chemical 

 and physical research in such directions as those which have 

 already been fruitful of most instructive results, such talented 

 labourers as Chernoff, Osmond, Roberts-Austen, Barus and 

 Strouhal, Hadfield, Keep, James Riley, Stead, Turner, and 

 others, cannot fail to contribute continually to the development 

 of improvements equalling in importance those already attained 

 in the production, treatment, and methods of applying cast-iron, 

 malleable iron, and steel, or alloys equivalent to steel in their 

 qualities. 



The causes of the variations in the physical properties of steel 

 produced by the so-called hardening, annealing, and tempering 

 processes were for very many years a fruitful subject of experi- 

 mental inquiry, as well as of theoretical speculation with regard 

 to the condition in which the carbon is distributed in steel, ac- 

 cording to whether the metal is hardened or annealed, or in an 

 intermediate, tempered state. Recent researches have made our 

 knowledge in the latter direction fairly precise ; as yet, however, 

 we are only on the track of definite information respecting the 

 nature and extent of connection between the physical peculiarities 

 of steel in those different conditions and the established differences 

 in the form and manner in which the carbon is disseminated 

 through it. 



The careful systematic study of the modifications developed in 

 certain physical properties of iron and steel by gradual changes 

 of temperature between fusion of the metal and the normal 

 temperature, has shown those modifications to be governed by a 

 constant law, and that at certain critical temperatures special 

 phenomena present themselves. This important subject, which 

 was so clearly brought before the Association last year in the 

 interesting lecture of Roberts-Austen, has been, and is still 

 being pursued by accomplished workers, among whom the most 

 prominent is F. Osmond. The phenomenon of recalescence. or 

 the re-glowing of, or liberation of heat in, iron and steel at 

 certain stages during the cooling process, first noticed by Gore, 

 and examined into by Barrett, appears to be the result of actual 

 chemical combination between the metal and its contained carbon 

 at the particular temperature attained at the time ; while the 

 absorption of heat, demonstrated by the arrest in rise of tempe- 

 rature during its continuous application to the metal, is ascribed 

 to the elimination, within the mass, of carbon as an iron-carbide 

 perfectly stable at low temperatures. The pursuit of a well- 

 devised system of experimental inquiry into this subject has led 

 Osmond to propound theories of the hardening and tempering 

 of steel, which are at present receiving the careful study of 

 physicists and chemists, and cannot fail to lead to further im- 

 portant advancement of our knowledge of the true nature of the 

 influence of carbon upon the properties of iron. 



Another important subject connected with the treatment of 

 masses of steel, and with the influence exercised upon their 

 physical characteristics by the processes of hardening and tem- 

 pering, and by submitting them to oft-repeated concussions or 

 vibrations, or frequent or long-continued strains, is the develop- 

 ment and maintenance, or gradual disappearance, of internal 

 stresses in the masses — one of the many important subjects to 

 which attention was directed by Dr. Anderson, the Director- 

 General of Ordnance Factories, in his very suggestive address 

 to the Mechanical Section last year. This question is one of 



