September i8, 1919] 



NATURE 



59 



I may perhaps mention here that long ago, when 

 the cause of X-rays was a subject of speculation and 

 the doctrine that mainly found acceptance was that 

 they were not light-waves at all, I suggested to the 

 late Prof. Viriamu Jones that radiation of extremely 

 small wave-length would be produced if atomic or 

 molecular vibration, as distinguished from what in 

 comparison might be called molar vibration, could 

 be excited. An illustration that suggested itself was 

 this : — ^Take a vibrator composed of a series of small 

 masses with spring connections. If these masses are 

 of atomic or molecular dimensions any ordinary 

 impulse or impact would leave them unaffected, while 

 vibrations of groups of them, depending on the con- 

 nections, would result. But the impact on one of 

 the masses of a hammer of suflficiently small dimen- 

 sions and mass would give vibrations depending on 

 the structure of the mass struck, and independent of 

 the connections, just as the bars of a xylophone 

 ring, while the suspended series of bars, if it swings 

 at all, does so without emitting any audible sound. 

 This is, I believe, in accordance with the theory now 

 held as to X-ravs. We now have some information 

 as to the mode of producing a local excitement so 

 intense as to cause, not merely atomic disturbance, 

 but actual disruption of the atomic structure. Further 

 developments of Sir Ernest Rutherford's experiments 

 and of his theory of their explanation will be eagerly 

 awaited. 



SECTION B. 



CHEMISTRY. 



Opening .Address by Prof. P. Phillips Bedson, 

 D.Sc, President of the Section. 



In again taking up the work of this section, after 

 an interval of three years, a discontinuity without 

 parallel in the annals of the association, it is natural 

 that our thoughts should turn to the past, and in so 

 doing we are reminded of the gaps in the ranks of 

 those wh:> were accustomed to contribute to the work 

 of our section. In 1916 we met under a shadow 

 caused by the death of Sir W. Ramsay, whose genius 

 added in so many ways to our science. And 

 to-day we have to record the loss of one who in his 

 lung life contributed in a variety of ways to the 

 iulvancement of chemistry, and to whom we owe an 

 addition to the number of elementary substances in 

 the discovery of thallium, one of the early fruits of 

 the use of the spectroscope. The chemistry of the 

 rare earths has been, especially illumined by the re- 

 searches of Sir William Crookes. With physicists we 

 would join in a tribute to the memory of Lord Ray- 

 kigh, amongst whose experimental researches is one 

 of special interest to chemists, namely, the revelation 

 of the existence of argon, of which discovery Sir J. J. 

 Thomson has recently written that it was not made 

 "bv a happy accident, oc by the application of new 

 and more powerful methods than those at the dis- 

 posal of his predecessors, , but by that of the oldest of 

 chemical methods: the use of the balance." 



In this connection it is but right that, despite the 

 feelings engendered by the war, I should refer to the 

 passing of two great chemists — Baeyer and Fischer. 

 The former died some two years ago, and the latter 

 within the past two months. Each of them ad- 

 vanced by his experimental researches the progress 

 of organic chemistry, and brought illumination into 

 many of the obscure departments of this branch 

 of science. The field of investigation latterly cul- 

 tivated by Fischer has revived an interest in the 

 "vital" side of organic chemistry as distinguished 

 from the study of chemistry of the carbon compounds. 

 Moreover, there are many British chemists, amongst 

 NO. 2603, VOL. 104] 



them some of the most distinguished, who, as 

 students, received guidance and inspiration from the 

 teaching of Baeyer or of Fischer, and with them we 

 gratefully acknowledge our indebtedness. 



Fifty years ago Mendeldeff communicated to the 

 Russian Chemical Society a memoir which has exer- 

 cised a profound influence on chemical philosophy, 

 and continues to serve as a guide in the interpreta- 

 tion of research and speculations on the nature of 

 the elements. Without entering on the somewhat 

 vexed question as to whom should be assigned the 

 credit of the discovery of the periodic law, I trust I 

 shall not be considered unmindful of the claims of 

 Newlands by adopting the traditional history, and, as 

 is usual, associate this discovery with the' name of 

 Mendeli^eff, and consequently we may look on this 

 year as the jubilee of the periodic law. Although 

 there is already abufidant special literature dealing 

 with this subject, and the periodic system has been 

 assimilated into the teaching of the science, and is 

 dealt with in the text-books of chemistry, in some 

 of which it forms the basis of the system employed in 

 the exposition of the facts and theories of inorganic 

 chemistr)', still it appeared to me that I might utilise 

 this as an opportunity of passing in brief review some 

 of the features of the rise and development of the 

 "periodic law." 



The memoir, made known to the non-Russian 

 reader by the abstract in German, shows the prin- 

 ciple of periodicity, viz. the recurrence of similar pro- 

 perties at regular intervals with increase in the magni- 

 tude of atomic weights, the possibility of utilising the 

 atomic weights as a basis of the classification of the 

 elements, the necessity for the revision of the values 

 thus assigned to the atomic weights of certain 

 elements, and finally that the scheme demanded for 

 its completeness the existence of manv new elements. 



The later writings of Mendel^eff contain the mode 

 of tabulating the . elements in the form usually 

 adopted in chemical text-books, portraying the prin- 

 ciple of periodicity and showing the grouping of the 

 elements into natural families. But undoubtedly the 

 clearest demonstration of the association between the 

 atomic weights and the physical properties of the 

 elements is that exhibited by the curve of atomic 

 weights and atomic volumes, which is an outcome 

 of the independent studies of these relationships bv 

 Lothar Meyer, and, as is well known, shows the 

 members of the natural families of elements occupy- 

 ing corresponding positions on the curve. This curve, 

 with its undulations, corresponding with the series of 

 the elements, has contributed to impress on the mind 

 of the student the relationship between the properties 

 of the elements and their atomic weights, and may 

 have exercised an influence in directing attention to 

 these relationships which the attempts of the earlier 

 workers in this field were not successful in doing. 



MendeMeff's table of the elements was just 

 beginning to figure in the teaching of chemistry in 

 my undergraduate days, and, together with the 

 speculations underlying it, aroused considerable 

 interest and proved an incentive and inspiration for 

 experimental inquiry. Foremost in this country 

 amongst those who bv their writings have contributed 

 to spread a knowledge of Mendel^ff's speculations 

 was my fellow-student, Carnelley. His experimental 

 investigations added materially to our knowledge and 

 definition of the physical properties of elements and 

 compounds, which further emphasised the periodicity 

 in the relation of the atomic weights to the properties 

 of the elements, and have provided data from which 

 curves, resembling in contour the a'tomic volume 

 curve, have been set up. 



A valuable guide in fixing the atomic weights of 



