384 



NATURE 



[July 17, 19 19 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



Electro-Atomic Phenomena in the Magnetic Field. 



I HOPE you will grant me the opportunity of 

 making some brief observations on an article which 

 appeared in the issue of Nature for April 3, in which 

 the anonymous reviewer " N. R. C." delivers a judg- 

 ment of exceptional severity on one of my publications, 

 " Electro-atomic Phenomena under the Action of the 

 Magnetic Field," and for that reason very different 

 from the other judgments which have come to my 

 notice. 



I shall limit myself to a few points with the aim, 

 not of inducing the reviewer to change his opinion, 

 but of facilitating somewhat an equitable estimate by 

 readers of Nature, which is so widely diffused and 

 read by so many cultivated persons who are not 

 occupied in any particular way with physics. 



The reviewer seems unwilling to take into con- 

 sideration the fact that my book was written with the 

 sole purpose of bringing together and co-ordinating 

 my recent very numerous new experiments, of not 

 one of which (and this seems to me something im- 

 portant) has he been able to place the perfect validity 

 in doubt. Hence he has confined himself to attack- 

 ing the hypotheses proposed by me to account for the 

 new facts. He declares that he is occupied only with 

 the theory put forward to explain the facilitated ionisa- 

 tion by shock which I have demonstrated to take 

 place through the influence of the magnetic field. He 

 says, in fact : "This matter has been discussed less 

 thoroughly than the theory of magnetic rays." By 

 this he evidently intends to convey to the reader the 

 conviction that the latter theory has been destroyed by 

 the courteous objections of some physicists, to whom 

 I believe I opposed exhaustive, and not less courteous, 

 rectifications. 



The theory under examination at present consists in 

 this : Under the action of the field a gaseous molecule 

 tends to orient itself in such a manner that the force 

 due to the field, and acting upon a satellite electron, 

 acts towards the outside of the atom, and therefore 

 facilitates the liberation by shock of the electron itself. 

 H the atom has one single satellite electron, certainly 

 it will act in this manner, because it will be para- 

 magnetic according to the accepted theory. And the 

 behaviour of the air, which was the gas experimented 

 upon by me, is paramagnetic. 



Hence no one can succeed in understanding what 

 the question propounded by the reviewer means : 

 " How Prof. Righi arrives at a result so directly con- 

 trary (?) to that on which Langevin's theory of dia- 

 magnetism is based? According to the new theorv, 

 all atoms must be paramagnetic." As if I had de- 

 clared that I had obtained my results by experimenting, 

 not only on air, but also on diamagnetic gases, it 

 being granted that for the latter that objection 

 would have a serious value.. It is well to direct 

 attention to the fact that the reviewer seems to 

 believe that a diamagnetic substance orientates itself, 

 and in a sense opposite to a paramagnetic, in a 

 uniform field. 



It is a method of polemic unhappily sometimes 

 adopted (although rarely in scientific questions), this 

 of combating assertions which were not made; un- 

 fortunately, such a method can leave an unfavourable, 

 although unjust, impression on the great majority of 

 readers. 



NO. 2594, VOL. 103] 



Furthermore, if (and this is not at present the case) 

 there should some day be presented any facts con- 

 travenmg the theory of Langevin, it need not be 

 necessary to choose between this and another theory; 

 so long the nature of the connections, in virtue of 

 which the tendency of the trajectory of an electron 

 to orient itself in a given manner influences the 

 orientation of the entire atom, remain still indeter- 

 minate. 



I refrain from noticing the final hint on the typo- 

 graphical quality of my book. It is not clear whe'ther 

 this constitutes an unjust estimate of the sacrifices 

 undergone by my country during the recent war— in 



.which case I should protest with all my soul or 



whether it is nothing but a witticism in somewhat 

 questionable taste, intended to raise a contrast between 



the external aspect of the book and its contents in 



which case I would leave the judgment to readers of 

 Nature. Augusto Righi. 



Bologna (Italy), April, 1919. 



I AM certainly sorry that Prof. Righi should regard 

 my review as of "exceptional severity." It is true 

 of course, that more space is occupied in it by 

 criticism than by the expression of approval ; but this 

 is simply due to the fact, familiar to every reviewer, 

 that while_ the good features of a work can often be 

 described in a single sentence, many sentences are 

 usually necessary to explain why a less favourable 

 view is taken of other features. It was not my inten- 

 tion to imply that the book is without value, and I 

 cannot help thinking that Prof. Righi has— uninten- 

 tionally, of course— adopted the practice which he 

 deprecates of " combating assertions which were not 

 made." 



I am not at all "unwilling to take into considera- 

 tion the fact that the book was written with the pur- 

 pose of co-ordinating very numerous new experiments." 

 I stated, and I repeat, that Prof. Righi " has recorded 

 a large number of interesting and suggestive facts, 

 which deserve the close attention of all students of 

 physics." What more could I say, unless I proceeded 

 to give an account of these facts — a task which is 

 entirely unnecessary and obviously impossible in any 

 reasonable space? Again, when I said that "this 

 matter has been discussed less thoroughly ..." I 

 " intended to convey " nothing but a bare statement 

 of fact which provided a reason for the choice of one 

 portion of the work rather than another for more 

 detailed discussion. So far as I can ascertain by an 

 examination of the literature, there are much fewer 

 papers dealing with Prof. Righi 's theory of magneto- 

 ionisation than with his theory of magnetic ravs. If 

 I have overlooked some of the literature, I apologise; 

 but if I have not, it is not my fault that one of the 

 theories has received more attention than another. 



No useful purpose would be served by a further 

 elaboration of my criticism of Prof. Righi 's theory'. 

 A reviewer is surely not only entitled, but in duty 

 bound, to record his difference of opinion from the 

 author on anv matter which is essential to the work 

 reviewed ; in doing so he does not condemn the author, 

 but merely invites those interested in the matter to 

 read the work and to judge between the conflicting 

 opinions. Prof. Righi has expressed his opinion in 

 his book, and I have indicated mine very briefly in 

 my review; if there is to be further discussion, it had 

 better take place in the normal manner in technical 

 journals. 



But perhaps I may add a few words in further 

 explanation of my reference to Prof. Langevin's 

 theory. According to that theory, when a revolving 

 electron is introduced into a magnetic field, the radius 

 of the orbit is unchanged, but the angular velocity is 



