4/8 



NATURE 



[October 13, 19 10 



Brooks, by E. A. Andrews. Hutchinson and Co. — Photo- 

 graphy (Concise Knowledge Library), edited by H. P. 

 .Maslvell and others ; The Wonders oi the World, in parts, 

 illustrated. Crosby Lockwood and Son. — Short Specifi- 

 cations of Materials, Labour, and Goods for Works Con- 

 nected with Building, J. Cubitt ; Houses, Villas, and 

 I5ungalows for Britishers and .Americans .Abroad, G. G. 

 .Samson. Longmans and Co. — A History of the Cavendish 

 Laboratory, Cambridge, Various Writers, illustrated. 

 Macmillan and Co., Lid. — Tennyson as a Student and 

 Poet of Nature, Sir Norman Lockyer, K.C.B., F.R.S., 

 and W. L. Lockyer, with an introduction and notes ; 

 The Conservation of Natural Resources in the United 

 -States, C. R. Van Hise, illustrated. John Murray. — 

 British Weights and Measures, as described in the Laws 

 of England from Anglo-Saxon Times, Col. Sir C. M. 

 Watson. Kegan Paul and Co., Lid. — Educational Psj'cho- 

 logy, Prof. E. L. Thorndike. Swan Sonnenschein and 

 Co., Ltd. — .A translation of Hegel's Phenomenology of 

 Mind, J. B. Baillie, 2 vols. ; Thought and Things : a Study 

 of the Development and Meaning of Thought or Genetic 

 Logic, Prof. J. M. Baldwin, vol. iii.. Real Logic ; Matter 

 and Memory, H. Bergson, translated under the author's 

 supervision by N. M. Paul; -Adolescence, J. W. Slaughter; 

 Physiological Psychology, Prof. W. Wundt, a translation 

 of the fifth and wholly rewritten German edition by Prof. 

 E. B. Titchener, in 3 vols., vol. ii., illustrated ; and new 

 editions of The History of .'Esthetic, Dr. B, Bosanquet ; 

 Riddles of the Sphin.K : a Study in the Philosophy of 

 Humanism, Dr. F. C. S. Schiller; Darwinism and the 

 Humanities, Prof. J. M. Baldwin (Ethical Library). 

 Williams and Norgate. — A popular edition of Herbert 

 Spencer's First Principles, 2 vols. 



THE INTERNATIONAL CONGRESS ON 

 RADIOLOGY AND ELECTRICITY. 

 'T'HE second congress on radiology and electricity was 

 held at Brussels on September 13-15. That two 

 congresses have already been held to consider questions 

 relating to radio-activity and allied subjects affords evidence 

 of the rapid progress in this branch of science of recent 

 years ; but that some five hundred workers in physics and 

 medicine should have assembled to discuss the bearing of 

 modern electrical theory and radio-activity upon the various 

 investigations on which they are engaged is a striking 

 proof of the influence which these new ideas have exercised 

 on the progress of science. It is now universally felt to be 

 desirable, if not necessary, that those engaged on investi- 

 gations in radio-activity in different parts of the world 

 should have occasional opportunities of meeting each other, 

 and perhaps one of the most important results of the 

 recent congress has been the formation of an influential 

 international committee to arrange the time and place of 

 subsequent congresses. The continuation at regular 

 intervals of meetings such as the one which has just taken 

 place is therefore now assured, and thanks are due to 

 the Belgian men of science and to the Belgian Govern- 

 ment, under the patronage of which the congress was 

 held, for organising the two successful meetings, the 

 first at Lic'ge in 1005 and the second at Brussels this year. 

 It may be added that the meeting was rendered the more 

 successful and pleasant by the hospitality offered to 

 members by the tow^n of Brussels. In this connection may 

 be mentioned the reception at the Bourse and at the Town 

 Hall by the Municipality, and also the admirable perform- 

 ance at the Th^'atre Royal de la Monnaie, at which 

 m-'mbers were invited to be present. 



The work of the congress began on Tuesday, Sep- 

 tember 13, with a meeting at the Palais des Fetes in the 

 exhibition grounds, when members assembled to hear an 

 address by the president. Prof, de Heen, on cether and 

 matter. The large gathering included eminent men of 

 science from all parts of the world. The opening meeting 

 finished, members dispersed to spend the remainder of the 

 morning in the exhibition, after which they reassembled 

 in the buildings of the Free University for a meeting which 

 proved of exceptional interest. The proceedings began 

 with a discussion, opened by Prof. Rutherford, on the 

 question of fixing a suitable nomenclature in radio-activity 

 -and of establishing radio-active standards adapted to the 



NO. 2137, VOL. 84] 



requirements of quantitative measurements to be made for 

 physical and medical purposes. After a short discussion 

 it was decided that the matter could best be settled by a 

 small committee acquainted with the needs of the different 

 branches of the subject, and that this committee should 

 meet and report to the congress the results of their delibera- 

 tions at a subsequent meeting. The report of the com- 

 mittee is of such special interest that it is not possible to 

 deal adequately with it within the limits of this article, 

 but a full account of the recommendations was given by 

 Prof. Rutherford in Nature of October 6. While the 

 necessary arrangements were being made for the formation 

 of this committee the president called upon Madame Curie 

 to give an account of the recent experiments made in Paris 

 to isolate metallic radium. It will be remembered that 

 this metal has hitherto not been separated from its salts, 

 although a radium amalgam was obtained some years ago 

 by Coehn. The beautiful experiments described by 

 Madame Curie, resulting in the isolation of metallic 

 radium, must be regarded as a triumph in chemical 

 manipulation when it is remembered that, in addition to 

 the fact that on account of its chemical properties radium 

 is difficult to isolate, the operations had to be carried out 

 with minute quantities of material in such a way as to 

 avoid loss of the precious substance during the process. 

 These experiments should remove all possible doubt that 

 radium is, in fact, an element belonging to the same group 

 of metals as barium. 



.After some other communications the meeting adjourned 

 until the following day, when the congress met in three 

 sections to deal with the large number of papers on the 

 physical and medical aspect of radiology. The work of 

 the physical section was of great interest. It began with 

 a lecture, remarkable for the clear and vivid style of its 

 delivery, by M. Perrin, who described his experiments on 

 Brownian movement and their bearing on the determina- 

 tion c>f atomic magnitudes, followed by a review of the 

 present position of our knowledge of these matters. Dr. 

 Hahn next gave an account of the method of preparation 

 of some highly active samples of radiothorium and meso- 

 thorium, of which specimens were shown. The phos- 

 phorescent elTects produced by them on a zinc-sulphide 

 screen could be clearly seen from all parts of the lecture- 

 room, and there can be no doubt that these products, which 

 are n'ow to be had from Messrs. Knoffler'and Co., of 

 Berlin, will prove of great use for many purposes as an 

 alternative to radium. Mr. Soddy followed with a descrip- 

 tion of the results of his work on the rate of production 

 of helium from a Portuguese specimen of autunite. From 

 his experiments it is possible to assign limits between 

 which must lie the " life " of ionium, that stable product 

 discovered by Boltwood, and known to be the parent of 

 radium. 



The papers which remained to be rend on the last day 

 were so ninnerous that it was found necessary at the last 

 moment to subdivide the meeting further, and a separate 

 section was quickly formed under the presidency of Prof. 

 Rutherford for the discussion of purely radio-active ques- 

 tions. -A number of important papers on various subjects 

 were read. The proceedings were opened by Prof. Bragg 

 with a discussion of the nature of the y rays, in which 

 he showed how it is possible to assign a " range " to the 

 path of (3 rays in different metals on the assumption that 

 the 7 rays are material particles, and that the ionisation 

 produced by them is due to ;8 rays produced in their path. 

 The paper was immediately succeeded by one by Prof. 

 Barkia, who explained how each element submitted to a 

 stream of homogeneous X-ravs emits several beams of 

 homogeneous X-rays characteristic of the element. Each 

 homogeneous radiation was excited by a primary radiation 

 of greater penetrating power according to Stokes's law 

 for fluorescence, so that it was possible to draw a close 

 comparison between light and X-rays in this respect. Dr. 

 Hahn then gave an account of his experiments with Dr. 

 Baeyer on the magnetic deflection of $ rays. Photographs 

 were shown indicating that the deflected rays from a 

 single radio-active product gave rise to definite lines on 

 the photographic plate, showing that during the decay of 

 radio-active substances, just as for the o particle, the $ 

 particles leave the atom with a velocity characteristic of 

 the particular product. The question of the recoi' of 



