INTERNAL ARCHITECTURE OP METALS.

Otago Daily Times, Issue 13857, 21 March 1907, Page 10

INTERNAL ARCHITECTURE OP METALS.

INTERESTING -FACTS AND THEORIES. Under the. heading of "Scientific Note.?." in the Pall Mall Gazette, "C. \V. S." writes as follows: — The reader is already familiar with the idea that in these days of rapidly multiplying universities, the principle of specialisation must be adopted within reasonable limits. Of course, it, would be a lamentable thing if tho University of Sheffield, result of injuries caused by her clothes for instance, existed to study nothing in the world but- sleel, as it would l>e a lamentable thing if science wore totally ignored at Oxford. But the time has certainly come when cach university that is to gain or preserve a reputation for character must specialise in something. The University of London, for instance, is predestined to specialise in medicine as a direct consequence of tho nature anil size of tho metropolitan population; whilst the University of Sheffield does well to devote special attention to metallurgy. This last science has lately luade very great strides in Sheffield, and I suppose that not even in Germany or America- is there any school that can claim superiority over Hie Sheffield School of Metallurgy. The reader who is inclined io snilf at this subject may be reminded of two considerations—one. that the maintenance of his life daily depends in half a hundred circumstanccs upon (lie efficiency of practical metallurgy; and tho other, thai there is, to say the least, a most, remarkable correspondence between the development of human society and tho development of metallurgical knowledge. Yon really must not sniff at metallurgy unless you aro prepared io advocate a return to the good old days of the Stone Ago. One of the most successful lectures delivered at tho Royal Institution last winter was that upon "tho internal architecture of metals." by Professor J. O. Arnold, the chief of the Sheffield School of Metallurgy. An abstract of that- delightful discourse has lately been printed, and is well worthy of further mention here. The idea that metals have an internal architecture at all will bo novel to many, though those who take an interest in motor cars cannot bo long before ihey discover that there may bo all the practical difference in the world between one sloel rod and another. As Professor Arnold says, "(ho title of tho discourse may seem to some far-fetched, since superficially a. bar of polished brass or steel apparently presents tho archetype of a homogeneous solid." Yet, in point of fact, such a metal bar, which seems so absolutely continuous in structure, is composed of crystals, upon the relation of which lo 0110 another will depend nearly all thoso metallic properties that aro of such great practical importance. In this field of study the microscope has been of the ut-mcst value. _ We commonly think of this as a biologist's instrument. So it was primarily, and so it still is in ils most important, applications, yet the physicist and chemist, havo lately 'turned it to splendid account; and, it the truth wero known, I fear that some of them would bo very much amused to see the kind of microscopic apparatus which many medical men and pathologists, for instance, .regard as quite satisfactory and up-to-date. It is the physicists who have developed the microscope to .what surely cannot he very far from ils utmost limits, and especially with regard to this question of tho minute structure of metals, alloys, and so on. According lo Professor Arnold, however, llio limits of usefulness of the microscope havo been reached. "The microscope, after rendering great services, has, in its turn, broken down, mainly owing to the fact ihat optical examinations associaletl with transmitted light cannot be applied io opaque objects. and in more senses than one tho scientific metallurgist cannot yet see through steel." ■

. Everyone who shaves must take. "a. little interest in Iho so-callcd fatigue of metals, a subject which is ot extraordinary interest, because nr>t. inorelv of Professor Arnold's satirical definition that fatigue is "a generic term used clearly to explain all eases of fracture which arc not understood," but also because, it bears upon ihe work regardins "response in the living and not-living," which Dr Chundra liose has been doing for fiomo years. Professor Bose believes in the continuity of responsive phenomena in tho organic and the inorganic"; and he would lia.ro us believe that fatigue is really one and tho same phenomenon, whether it be found in a piece cf tin. a slice of turnip, or 11 man. No doubt the work of the Indian phvsicist is extremely interesting and important. Tho facts which he has registered are well worthy of recognition, but I fancy that such a metallurgist, as Profe-'sor Arnold would not be inclined to lay any such stress upon Hie analogy as Dr Boso thinks warranted. Doubtless, every year brines us further evidence of the continuity between tho inorganic and tho oraanic, but, we must not do violence to Facts, even in support of tho truest conceptions. and we mu4 also beware of being misled by language. That the.vo is in the very last resort more than a. supcrfieio' resemblance l>ctween so-called fatigue in a metal and the fatigue which this subject would induce in tile writer if he were not interested in it, wo mav possibly believe, but the metallurgical explanation would bo

in vastly different t-erras from the physiological explanation, and whilst, like the wise of all time, wc endeavour to keep our eyes open to tjio fundamental unity of things, wo must not underrate the importance o! difference.