September 29, 1904] 



NA TURE 



52; 



i-Iiminated. " Special " steels contain other elements, 

 or contain the ordinary elements in unusual propor- 

 tions, as in the well known examples of Mushet's air- 

 hardening tungsten steel, Hadfield's manganese steel, 

 railway t)re chrome steels, nickel chrome armour 

 plate steels, and so on, until at the present day, besides 

 the elements just indicated, aluminium, copper, 

 inolybdenum, and even vanadium, which last is dearer 

 than silver, are added to steels for commercial purposes, 

 while other alloys are under experiment. It may well 

 be imagined, then, with what eagerness the metal- 

 lurgist turns to a monograph on any series of special 

 steels, and particularly if it happens, as in the present 

 case, to be written by a well known worker on the 

 subject. Perhaps the title may mislead some genera! 

 inquirers, for no doubt we are all looking for accounts 

 of the experience of others in the innumerable appli- 

 cations, some experimental, some well established, of 

 the steels of lower nickel content; but unless they were 

 looking merely for guidance in the immediate work 

 of manufacturing or using those steels, the feeling of 

 disappointment would give way to one of great interest 

 at the thorough manner in which certain properties 

 of the steels of higher nickel content are discussed. 



Practically the only steels seriously considered are 

 those containing more than 26 per cent, of nickel. 

 Within limits these are "reversible alloys," that is, 

 " when they are brought to a determined temperature 

 after having been run through any cycle of tempera- 

 tures they retake sensibly the same properties." It 

 is interesting to note that these alloys 

 " take a beautiful polish, lend themselves admirably 

 to engraving, are sufficiently elastic when cold rolled 

 to make passable springs though sensibly inferior to 

 those of steel hardened and tempered. Resistance to 

 oxidation varies with the nickel content and for well 

 polished bars it is sufficient to go up to 36 per cent, 

 nickel in order to be able without fear to leave them 

 lying some hours or even days in water at ordinary 

 temperatures. The reversible alloys work well in the 

 lathe, in the planing machine, with the file or the drill 

 on condition that the tool be strong and the attack 

 slow. In general, working at too great a speed makes 

 Ihe alloys act in the same fashion as a grindstone and 

 produces an extremely rapid wearing of the steel tool." 



The work consists of four parts and an appendix. 

 Part i. gives the dilatation and modulus of elasticity 

 of the reversible alloys, and goes into great detail as 

 to the amounts and variations of these under special 

 conditions. These properties of the alloy of least 

 dilatation containing about 36 per cent, of nickel, and 

 the special annealing at temperatures less than 100° C. 

 required to bring its wonderfully low dilatation 

 practically to zero, and to bring almost to perfection 

 its invariability under the greatest extremes of atmo- 

 spheric temperature known, are most carefully de- 

 scribed. Two new terms, widely accepted, should be 

 noted here, etuvagc for the low temperature anneal- 

 ing as distinct from recuit, high temperature 

 annealing, and invar, an appropriate name for the 

 ;ilIoy. 



Part ii. is devoted to the application of these alloys, 



and particularly of invar, to the making of standards 



of length, and more especially for the measurement of 



bases in survey work (see Nature, June 2, p. 104), 



NO. 1822, VOL. 70] 



ivith full details of the special wire standard. Part iii. 

 treats of the uses and the limitations of the alloys in 

 connection with chronometer pendulums, balances, and 

 even springs. Part iv. takes sundry applications, some 

 tried, some suggested, such as parts of levelling in- 

 struments, cathetometer and similar supports, bodies 

 of astronomical telescopes, gravitation pendulums, 

 balances, wires for operating signals, &c. Finally, the 

 existence of invar, an alloy with a dilatation practically 

 nil, suggests alloys of varying dilatations, hence 

 special alloys (42 per cent, to 48 per cent.), with an ex- 

 pansion about equal to that of glass, for mounts of 

 object glasses, incandescent lamps, Crookes's tubes, 

 &c. In an appendix of twenty-seven pages the author 

 gives his theory of the nickel steels. He abandons his 

 former theory of compounds of iron and nickel, and, 

 under the influence of MM. Osmond and Le Chatelier, 

 works out an allotropic theory, of which space will not 

 permit even a resume. 



This work is one that should be read not only by 

 those particularly interested in the special matters with 

 which it deals, but by all students of metals, as it 

 forcibly drives home to the mind some of the character- 

 istic properties of a remarkable series of alloys. 



A. McW. 



OUR BOOK SHELF. 



Le Radium et la Radioactivity. By Paul Besson. 



With a preface by Dr. A. d'Arsonval. Pp. viii-t-iyo. 



(Paris : Gauthier-Villars, 1904.) Price 3.75 francs. 

 This little volume is undoubtedly one of the best 

 summaries that has yet appeared of the investigations 

 that have followed from Becquerel's discovery, in 1896, 

 of the radio-activity of the salts of uranium. The 

 author has been associated with Prof, and Madame 

 Curie in working up on a large scale the uranium 

 residues from Joachimsthal, from which the salts of 

 radium were commercially prepared. His account of 

 the discovery of the radio-active elements, of their 

 separation from the inactive elements in the ores, and 

 of the methods employed in detecting and estimating 

 their radio-activity, is exceedingly lucid and simple, 

 and will appeal strongly to those who wish for a simple 

 account of the phenomena as they presented themselves 

 to the pioneer workers in this field of investigation. 

 In view of the large amount of speculation that these 

 investigations have aroused, it is one of the merits of 

 the book that, whilst seven chapters are devoted to the 

 description of the preparation and properties of the 

 radio-active salts, the theoretical considerations are 

 brought forward only in the last chapter. The dis- 

 integration theory, which at the present time dominates 

 almost all that is written on this subject, occupies only 

 a secondary place in the author's discussion of the 

 source of the energy of radio-active bodies. He 

 appears to lean rather to the view advocated by 

 Filippo Re in a short paper published in the Comptes 

 rendus in June of last year, to the effect that the radio- 

 active elements act as sources of energy not because 

 they are in an unstable or explosive condition, but 

 rather because they are still in process of formation. 

 This view, which is derived from analogy with the 

 liberation of energy in the solar system, has much to 

 recommend it, as it eliminates the difficulty of account- 

 ing for the relatively slow rate at which the elements 

 in question release the vast stores of energy which they 

 are supposed, by the advocates of the disintegration 

 theory, to contain. 



