May 2, 1895] 



NA TURE 



'7 



in the front rank. \\y points out' that Deprez- used in 1849, 

 the heat produced by the arc of a ])owerfuI i>ile ; but Moissan 

 was the first to employ the arc in sucti a way as to seixirate its 

 heating effect frcjni the electrolytic action it exerts. This he does 

 by placin;; the poles in a horizontal position, and by reflecting; 

 their heat into a receptacle below them. He has shown, in a 

 series of classical researches, that employing Soo ani])eres and 1 10 

 volts a temperature of at least 3500' may be attained, and that 

 many metallic oxides which until recently were supposed to be 

 irreducible may be readily made to yield the metal they contain.* 

 .\ support or base for the metal to be reduced is needed, and 

 this is afforded by magnesia, which appears to be absolutely 

 stable at the utmost temperatures of the arc. .Vn atmosphere of 

 hydrogen may l>e emjiloyed to avoid oxidatitm of the reduced 

 metal, which, if it is not a vcjlatile one, remains at the bottom of 

 the crucible almost always associated with carbon — forming, in 

 feet, a carbide of the metal. I want to show you the way in 

 which the electric furnace is used, but unfortunately the re- 

 ductions are usually very tedious, and it would be impossible to 

 actually show you much if 1 «ere to attempt to reduce before 

 you any of the rarer metals ; iiut as the main object is to show 

 you how the fvirnace is used, it may be well to hoil some silver at 

 a temperature of some 2500", and subseijuently to melt chromium 

 in the furnace (Fig. 2). This furnace consists of a clay receptacle, 

 A, lined with magnesia, B. .\ current of 6oamperes and 100 volts 

 is introduced by the carbon poles, r, i: ; an electro-magnet, M, is 

 provided lo defied the arc on to the metal to be melted. [By 



will render still greater services? My object in this lecture is 

 mainly to introduce you to these metals, which hitherto few of 

 us have ever seen except as minute cabinet specimens, and «e 

 are greatly indebted to M. Moissau fur sending us beautiful 

 specimens of chromium, vanadium, uranium, zirconium, tungsten, 

 molybdenum, ami lilanimn. (These were exhibited.] 



The<|uestion naturally arises : Why isthe futureof their useful- 

 ness so promising > Why are lln'y likely lo render belter service 

 than the conmion metals with which we have long been familiar? 

 It must be confessed that :vs yet wo know but little what services 

 these metals will render when they stand alone ; we have yet to 

 obtain them in a state of purity, and have yet lo study their pro- 

 perties, but when small quantitiesof any of them are associated or 

 alloyed with other metals, there is good reason to believe that 

 they will exert a very powerful influence, fn orfler to explain 

 this, I must appeal lo the physical method of ini|uiry to which I 

 have already referred. 



It is ea.sy to test the strength of a metal or of an alloy ; it is 

 also easy to determine its electrical resistance. If the nvtss stands 

 these tests well, its suitability for certain purposes is assured ; 

 but a subtle method of investigation has been afforded by the 

 results of a research entrusted to me bv a committee of 



,iigr-iv.jj;^ 



B 



means of a len> and mirror, u. K, the image of the arc and of the 

 molten metal was projected on to a screen. For this purpose it 

 was found convenient to make the furnace much deeper than 

 would ordinarily be the case. | 



It must not be forgotten thai the use of the electric arc between 

 carbon poles renders it practically impossible lo prepare the rare 

 metals without associating them with carbon, often forming true 

 carbides ; but it is possible in many c;ises to separate the carbon 

 by sul)sei|ueiit treatment. Moissan has, however, opened up a 

 va.sl field of industrial work by placing at our disposal jiractically 

 all the rarer infusible metals uliich may be reduced from oxides, 

 and it is necessary for us now to consider how vve may best enter 

 upon our inheritance. Those mendiers of the group which we 

 have known long encjugh lo appreciate are chromium and man- 

 •ganese, and these we have only known free from carbon for a 

 few months. In their carburised state they have done excellent 

 .service in connection with the metallurgy of steel ; and may we 

 ■not hope that vanadium, molybdenum, titanium, and uranium 



I Ann. de Clihii. el ,1c I'hys. vol. iv. 1895, p. 05. 



;- Canifites reiulns, v.il. x.vix. 1849, p. 48, 545, 712. 



'I he principal memoirs of Jl. .\Ioiss.m will be fouml in tlic ConiMcs 

 ««</<,.■, vol. «v. .89-., p ,03. ; ibid. vol. cxvi. ,893, pp. 347, 349,549, ,k-2, 

 l"5, .429; /W. vol. cxix. 189,, pp. ,5, .o. 935; /«/V>. vol. - 



ago. The more iiiiport:int of the " metal: 

 chromium. 



95. P- 



, 935 . 



he h.is isolated .ire uranium, 

 manganese, zirconium, molylHlenum, tungsten, v.-in.ldium, anil 

 «t.lniinn. I here is an important paper hv him on the various forms of the 

 eleclri.: fiirn.ice ni the Ann. ,/,■ Cliim. ,1 ,/,• /'/iy.>!. \<-,\. iv. 



No. 1,;;, 1, \nr,. ^2^ 



0.5. 1>. 365 



:*^ 



li«s7l 



w hich 1 )r. 

 now gather 



the Institution of Meclianical Kngineers, over 

 .\nderson, of Woolwich, presides. We can 

 much information as to the way in which a mass of inetal 

 has arranged il.self during the cooling from a molten condition, 

 which is the neces.sary step in ftshioning it into a useful form ; it 

 is possible lo gain insight into the way in which a molten mass 

 of a metal or an alloy, moleciilarly settles itself down to its work, 

 so to S[X!ak, and we can form <-oiiclusions as to its prolxible sphere 

 of usefulness. 



The method is a graphic one, such its this audience is familiar 

 with, for I'rof. Victor Ilorsley has shown in a masterly way that 

 traces on smoked [laper may form the leconl of the heart's action 

 under the disturbing influence caused by the intrusion of a bullet 

 into the human body. I hope to show you by similar records 

 the effect, which though disturbing is often far from pre- 

 judicial, of the introduction of a small i|uantity of a foreign 

 element into the ".system'' of a metal, and to justify a 

 statement whii-h I m.ade earlier, as to the applicability of 

 physiological methods of investigation to the study of metals. 

 In order that the nature .if this method may be clear, it 



