and those which aid in the destruction of dead vegetable and animal matter, play a very valuable and but little appreciated part in the continuance of the life and well being of man. There are many other ways in which the products of these dreaded microscopic cells are useful, but all, a very insignificant number of which we have mentioned, are only waiting man's bidding to become valuable subjects, and to show that, as has been instanced in the history of nations, conquered people often make the best and wisest citizens. THE RARER METALS AND THEIR ALLOYS.1 By Prof. W. CHANDLER ROBERTS-AUSTEN, C. B., F. R. S., M. R. I. For reason is not the only attribute of man, nor is it the only faculty which he habitually employs for the ascertainment of truth.-G. J. ROMANES. Appreciation.... by æsthetic and intellectual faculties which are not senses, and which are not unfrequently sadly wanting where the senses are in full vigor.-T. H. HUXLEY. The study of metals possesses an irresistible charm for us, quite apart from its vast national importance. How many of us made our first scientific experiment by watching the melting of lead, little thinking that we should hardly have done a bad life's work if the experiment had been our last, provided we had only understood its full significance. How few of us forget that we wistfully observed at an early age the melting in an ordinary fire of some metallic toy of our childhood; and such an experiment has, like the "Flatiron for a farthing," in Mrs. Ewing's charming story, taken a prominent place in literature which claims to be written for the young. Hans Andersen's fairy tale, for instance, the "History of a tin soldier," has been read by children of all ages and of most nations. The romantic incidents of the soldier's eventful career need not be dwelt upon; but I may remind you that at its end he perished in the flames of an ordinary fire, and all that could subsequently be found of him was a small heart-shaped mass. There is no reason to doubt the perfect accuracy of the story recorded by Andersen, who at least knew the facts, though his statement is made in popular language. No analysis is given of the tin soldier; in a fairy tale it would have been out of place, but the latest stage of his evolution is described, and the record is sufficient to enable us to form the opinion that he was composed of both tin and lead, certain alloys of which metals will burn to ashes like tinder. His uniform was doubtless richly ornamented with gold lace. Some small amount of one of the rarer metals had probably-for on this point the history is silentfound its way into his constitution, and by uniting with the gold formed the heart-shaped mass which the fire would not melt, as its Read at weekly evening meeting of Royal Institution of Great Britain, March 15, 1895. Printed in Proceedings of the Institution, Vol XIV, pp. 497–520. SM 96-32 497 temperature could not have exceeded 1,000° C.; for we are told that the golden rose worn by the artiste who shared the soldier's fate was also found unmelted. The main point is, however, that the presence of one of the rarer metals must have endowed the soldier with his singular endurance, and in the end left an incorruptible record of him. This incident has been taken as the starting point of the lecture, because we shall see that the ordinary metals so often owe remarkable qualities to the presence of a rarer metal which fits them for special work. This early love of metals is implanted in us as part of our "unsquandered heritage of sentiments and ideals which has come down to us from other ages," but future generations of children will know far more than we did; for the attempt will be made to teach them that even psychology is a branch of molecular physics, and they will therefore see much more in the melted toy than a shapeless mass of tin and lead. It is really not an inert thing; for some time after it was newly cast it was the scene of intense molecular activity. It probably is never molecularly quiescent, and a slight elevation of temperature will excite in it rapid atomic movement anew. The nature of such movement I have indicated on previous occasions when, as now, I have tried to interest you in certain properties of metals and alloys. This evening I appeal incidentally to higher feelings than interest by bringing before you certain phases in the life history of metals which may lead you to a generous appreciation of the many excellent qualities they possess. Metals have been sadly misunderstood. In the belief that animate beings are more interesting, experimenters have neglected metals, while no form of matter in which life can be recognized is thought to be too humble to receive encouragement. Thus it is that bacteria, with repulsive attributes and criminal instincts, are petted and watched with solicitude, and comprehensive schemes are submitted to the Royal Society for their devolopment, culture, and even for their "education," which may, it is true, ultimately make them useful metallurgical agents, as certain micro-organisms have already proved their ability to produce arseniuretted hydrogen from oxide of arsenic.2 It will not be difficult to show that methods which have proved so fruitful in results when applied to the study of living things are singularly applicable to metals and alloys, which really present close analogies to living organisms. This must be a new view to many, and it may be said, "it is well known that uneducated races tend to personify or animate external nature," and it is strange, therefore, to attempt, before a cultured audience, to trace analogies which must appear to be remote between moving organisms and inert alloys, but Dr. Percy Frankland especially refers to the "education" of bacilli for adapting them to altered conditions. Roy. Soc. Proc., Vol. LVI, 1894, page 539. * Dr. Brauner. Chem. News, Feb. 15, 1895, page 79. "the greater the number of attributes that attach to anything, the more real that thing is." Many of the less-known metals are very real to me, and I want them to be so to you; listen to me, then, as speaking for my silent metallic friends, while I try to secure for them your sympathy, esteem, and intuitive perception of their beauty. First, as regards their origin and early history. I fully share Mr. Lockyer's belief as to their origin, and think that a future generation will speak of the evolution of metals as we now do of that of animals, and that observers will naturally turn to the sun as the field in which this evolution can best be studied. To the alchemists metals were almost sentient; they treated them as if they were living beings, and had an elaborate pharmacopoeia of "medicines" which they freely administered to metals in the hope of perfecting their constitution. If the alchemists constantly drew parallels between living things and metals, it is not because they were ignorant, but because they recognized in metals the possession of attributes which closely resemble those organisms. "The first alchemists were gnostics, and the old beliefs of Egypt blended with those of Chaldea in the second and third centuries. The old metals of the Egyptians represented men, and this is probably the origin of the homunculus of the middle ages, the notion of the creative power of metals and that of life being confounded in the same symbol." 2 Thus Albertus Magnus traces the influence of congenital defects in the generation of metals and of animals, and Basil Valentine symbolizes the loss of metalline character, which we now know is due to oxidation, to the escape from the metal of an indestructable spirit which flies away and becomes a soul. On the other hand, the "reduction" of metals from their oxides was supposed to give the metals a new exist ence. A poem of the thirteenth century well embodies this belief in the analogies between men and metals, in the quaint lines: 3 Homs ont l'estre comme metaulx, Esprit comme ange en attributs. "Men have being "-constitution-like metals; you see how closely metals and life were connected in the minds of the alchemists, and we inherit their traditions. "Who said these old renowns, dead long ago, could make me forget the living world?" are words which Browning places in the lips of Paracelsus, and we metallurgists are not likely to forget the living Lotze, "Metaphysic," section 49, quoted by Illingworth. "Personality, Human and Divine." Bampton Lectures, 1894, page 43. Berthelot, Les Origines de l'Alchimie, 1885 page 60. 3 Les Remonstrances ou la Complainte de Nature a l'Alchymiste Errant. Attributed to Jehan de Meung, who with Guillaume de Lorris wrote the Roman de la Rose. M. Meon, the editor of the edition of 1814 of this celebrated work, doubts, however, whether the attribution of the complainte de nature, to Meung is correct. world; we borrow its definitions, and apply them to our metals. Thus nobility in metals as in men, means freedom from liability to tarnish, and we know that the rarer metals are like rarer virtues, and have singular power in enduring their more ordinary associates with firmness, elasticity, strength, and endurance. On the other hand, some of the less known metals appear to be mere "things" which do not exist for themselves, but only for the sake of other metals to which they can be united. This may, however, only seem to be the case because we as yet know so little about them. The question naturally arises, how can the analogies between organic and inorganic bodies now be traced? I agree with my colleague at the École des Mines of Paris, Prof. Urbain Le Verrier, in thinking that it is possible' to study the biology, the anatomy, and even the pathology of metals. The anatomy of metals—that is, their structure and frameworkis best examined by the aid of the microscope, but if we wish to study the biology and pathology of metals, the method of autographic pyrometry, which I brought before you in a Friday evening lecture delivered in 1892, will render admirable service, for, just as in biological and pathological phenomena vital functions and changes of tissue are accompanied by a rise or fall in temperature, so molecular changes in metals are attended with an evolution or absorption of heat. With the aid of the recording pyrometer we now "take the temperature" of a mass of metal or alloy in which molecular disturbance is suspected to lurk, as surely as a doctor does that of a patient in whom febrile symptoms are manifest. It has, moreover, long been known that we can submit a metal or an alloy in its normal state to severe stress, record its power of endurance, and then, by allowing it to recover from fatigue, enable it to regain some, at least, of its original strength. The human analogies of metals are really very close indeed, for, as is the case with our own mental efforts, the internal molecular work which is done in metals often strengthens and invigorates them. Certain metals have a double existence, and according to circumstances, their behavior may be absolutely harmful or entirely beneficial. The dualism we so often recognize in human life becomes allotropism in metals, and they, strangely enough, seem to be restricted to a single form of existence if they are absolutely free from contamination, for probably an absolutely pure metal can not pass from a normal to an allotropic state. Last, it may be claimed that some metals possess attributes which are closely allied to moral qualities, for, in their relations with other elements, they often display an amount of discrimination and restraint that would do credit to sentient beings. Close as this resemblance is, I am far from attributing consciousness to metals, as their atomic changes result from the action of external agents, while the conduct of conscious beings is not determined from La Métallurgie en France, 1894, page 2. |