NATURE 



THURSDAY, MAY 9, 1907. 



IS THE ELECTRONIC THEORY OF 

 MATTER LEGITIMATE? 



Electrons, or the Nature and Properties of Negative 



Electricity. By Sir Oliver Lodge, F.R.S. Pp. 



XV + 230. (London: George Bell and Sons, 1906.) 



Price 6x. net. 

 A T the present time there are few more absorbing 

 ■^* topics among physicists and chemists than the 

 electron and its relation to matter, and none on which 

 a more complete mystification exists. -A book on the 

 subject by so illuminating and inspiring a publicist 

 as Sir Oliver Lodge is therefore doubly acceptable 

 at the present time. 



A few words on the existing situation may be of 

 general interest. It will be recalled that the re- 

 searches in optics on the one hand, culminating in 

 the discovery and elucidation of the Zeeman effect, and 

 in the phenomena of the Crookes's tube on the other, 

 resulting in the isolation of the free electron and 

 the measurement of its constants by J. J. Thom- 

 son, made the scientific world familiar with the con- 

 clusion that the same electron or atom of negative 

 electricity is an ultimate constituent of all atoms, 

 and possesses, in virtue of the magnetic field it 

 creates in motion, inertia which, though small, is 

 definite and indistinguishable in ordinary circum- 

 stances from the inertia possessed by ordinary matter. 

 There is little that would to-day be generally con- 

 sidered as controversial in these two conclusions. On 

 the contrary, the researches which have led to them 

 have received the unstinted admiration of all. But 

 upon these conclusions are based others, concerned, 

 not with the nature of electricity, but of matter, in 

 the highest degree controversial and speculative, 

 which regard the electron as the universal unit out of 

 which all matter is essentially built up, and mass as 

 an electromagnetic phenomenon due to a vast 

 assemblage of constituent electrons grouped together 

 in stable configurations constituting the atoms. 

 This view of atomic structure was developed by J. J. 

 Thomson in two papers (Phil. Mag., December, 

 190J, and March, 1904). He regarded the atom as 

 composed of a uniform sphere of positive electrifi- 

 cation containing an electrically equivalent number 

 of electrons revolving in regular motion about the 

 centre, and showed that according to the numbers 

 of the electrons periodic sequences of properties of 

 the systems would occur strikingly similar to the 

 periodic sequences in the properties of the atoms of 

 the actual elements themselves. 



One of the most enthusiastic supporters of the 

 universal e.xtensicn of the electronic theory to explain 

 the properties of matter has been Sir Oliver Lodge 

 himself, who saw in the instability, natural to a 

 system constituted of electrons in constrained motion, 

 due to the external radiation of energy that must be 

 supposed to take place, a possible cause of radio- 

 activity and of the observed disintegration of the radio- 

 active elements. Some few months ago, however, 

 NO. 1958, VOL. 76] 



J. J. Thomson {Phil. Mag., June, 1906) published 

 the results of an investigation into the actual number 

 of electrons existing in an atom of matter by three 

 independent methods, which led to the uniform and 

 unexpected conclusion that the number of electrons 

 is of the same order as the weight of the atom in 

 terms of that of hydrogen as unity. Since then it 

 may be safely said that no one has known quite 

 what to think with regard to the electronic theory 

 in its apolication to material phenomena, and the pre- 

 sent book, from the pen of a writer to whom so often 

 in the past the student has looked for light and 

 leading in difficult places, will therefore be opened 

 with curiosity and read with eagerness. 



The effect of the profound changes which have 

 come over the subject in the last few months is 

 evident in the preface, where we read : — 



" A proof that the atom of matter is essentially 

 composed of such electrons, and that its mass, too. is 

 of purely electromagnetic nature, is lacking; the 

 electromagnetic theory of Matter . . . must be re- 

 garded for the present as no better than a working 

 hypothesis. It is a hypothesis of stimulating char- 

 acter, and of great probability, but its truth is still 

 an open question that is probably not going to be 

 speedily closed." 



The e.xtract may be said to give the keynote to 

 the treatment in the book. It is evident that the 

 writer himself has not lost confidence in the ultimate 

 triumph of the electron theory in its universal aspect, 

 and although he is aware of, and does not attempt 

 to minimise the magnitude of, the recent difficulties 

 which have arisen, his enthusiasm is still undamped. 

 In a chapter towards the end of the book, devoted to 

 a consideration of some of these difficulties, he him- 

 self describes the recent paper of J. J. Thomson, to 

 which reference has been made, as " the most serious 

 blow yet dealt at the theory, at least in its simpler 

 and cruder form" (p. 194); and again (p. 151), "it 

 has tended to reduce the whole subject to a state of 

 exaggerated uncertainty." But his final conclusion 

 is (p. 200) : — 



" The most exciting part of the whole is the explan- 

 ation of matter in terms of electricity, the view that 

 electricity is, after all, the fundamental substance, 

 and that what we have been accustomed to regard as 

 an indivisible atom of matter is built up out of it; 

 that all atoms — atoms of all sorts of substances — are 

 built up of the same thing. . . . But it must be re- 

 membered that although this solution is strongly 

 suggested it is not yet a completed proof. Much 

 more work remains to be done before we are certain 

 that mass is due to electric nuclei." 



No excuse need be offered for dwelling on this side 

 of the book, for the attitude of the leading exponents 

 to the recent developments of the electronic theory 

 of matter is topically the most interesting to the 

 scientific reader at the moment. But attention must 

 not on that account be diverted from what is, after 

 all, the main subject of the book, not the nature of 

 matter, but that of electricity. The major part is 

 devoted to an admirable and inspiring treatment of 

 those solid results of experiment and analysis eluci- 

 dating the nature and properties of negative electricity, 



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