January i, 1920] 



NATURE 



455 



law, which demands that the speed of light varies as 

 1-2O, where Q is the gravitational potential. He 

 showed that, whether Einstein's solution of the 

 problem be correct or not, it has, at any rate, given 

 a new orientation to our ideas of space and time. Sir 

 Oliver Lodge regarded the relativity theory of 1905 

 as a supplement to Newtonian dynamics by the adop- 

 tion of the factor (i — d^/c') and its powers necessitated 

 by e.xperimental results; but he did not consider this 

 dependence of mass and length on velocity as entailing 

 any revolutionary changes of our ideas of space and 

 time, or as rendering necessary the further complexi- 

 ties of 1915. He compared the difficulties involved 

 with the case of measuring temperature, defined in 

 terms of a perfect gas, and made with gases which 

 only approximate to this ideal state. Dr. Silberstein 

 pointed out that Einstein's theory of gravitation pre- 

 dicts three verifiable phenomena, i.e. a shift of spec- 

 tral lines, the bending of light round the sun, and 

 the secular motion of the perihelion of a planet. In 

 the neighbourhood of a radially symmetric mass such 

 as our sun, the line-element ds is given bv 



ds^ = (\-7.Ulc'-r)c^dfl-{,\-iWc^r)(dx^^iiy^-\-dz'). 

 The coefficient c^di' gives by itself a lengthening of 

 the period of oscillation for a terrestrial observer in 

 the ratio (i-fM/cV) : i, demanding a shift of spectral 

 lines of about 001 A.U. Secondly, the path of rays 

 of light is obtained by putting ds = o, and the first and 

 second coefficients give jointly a bending which for 

 rays almost grazing the sun is 1-75". Thirdly, Kep- 

 lerian motion is predicted with a progressivelv moving 

 perihelion, which in the case of Mercury turns out to 

 be 43" per century. He directed attention to the fact 

 that St. John's results in 1917 showed no shift of 

 the spectral lines, which in itself would overthrow 

 the theory in question. Father Cortie pointed out 

 that Campbell's photographs taken in 19 18 and 

 measured by Curtis gave no trace of any displacement 

 of the images of forty-three stars distributed irregu- 

 larly round the sun. 



.Amongst other papers read at the meeting mav oe 

 mentioned an account by Sir Frederick Stupart of 

 weather conditions in .Mberta and a paper by Prof. 

 Forsvth on Gauss's theorem. 



CHEMISTRY AT THE BRITISH 

 ASSOCI.4TION. 



T T was perhaps only to be expected that the pro- 

 ^ gramme of the Chemical Section should be 

 coloured by the four years of war through which we 

 had just passed, but, though war chemistry took a 

 prominent place, more academic subjects were not 

 entirely relegated to the background. 



Some excellent summaries of work in different 

 branches of chemistry during the war were given by 

 various speakers. 



Sir William Pope spoke on the general subject of 

 the position of chemistry in Germany and this countrv 

 as a result of the war, and pointed out that while 

 German chemical industries emerged from the war 

 in a strengthened position, ours remained much as 

 they were, and that we were faced with a great, 

 immediate danger in a strong propagandist move- 

 ment to rehabilitate the German chemist in the eyes 

 of the world. 



Rrig.-Gen. Hartlv^y described the development of 

 chemical warfare and the measures taken to counteract 

 its destructive effects bv means of gas-masks, etc. 

 This particular form of warfare is, perhaps, not so 

 inhuman as it is often regarded to be ; for if it be 

 Cranted that human lives must be sacrificed and suf- 

 fering endured to achieve military objectives, then such 

 NO. 2618, VOL. 104] 



objectives can often be attained by the use of gab 

 attacks, lachrymatory shells, etc., with less loss of 

 life and permanent injury than by the employment of 

 high explosives. 



Col. C. D. Crozier reviewed the output and methods 

 of manufacture of high explosives during the war, 

 directing attention to the improvements in method 

 and quality which took place as the exigencies of 

 the military situation called for an ever-increasing 

 output, and claimed that this result was due in no 

 small part to the activities of the Inspection Depart- 

 ment. 



Prof. Desch gave an excellent resumi of the metal- 

 lurgical position in this country and the Central 

 Empires, and showed how metallurgical considerations 

 entered into the Franco-German Peace of 187 1, and 

 largely influenced the war and the territorial re- 

 adjustments of the Peace Treaties. The necessities 

 of war, if without any striking metallurgical develop- 

 ments, have at any rate, so far as this Empire 

 is concerned, done much to stimulate the working 

 within the Empire of locally produced ores, 

 while fresh industries have arisen to smelt ores 

 of metals hitherto imported from enemv coun- 

 tries. In Germany, as might have been expected, 

 the study and use of substitutes for such metals as 

 copper, nickel, and manganese have received close 

 attention. 



.\ paper by Dr. M. W. Travers described the posi- 

 tion of the glass trade after the war. Though much 

 has been done to supply the demand for various kinds 

 of glass in this country. Dr. Travers must un- 

 doubtedly be written down as an optimist when he 

 declares we can now supply from home-made stock 

 all requirements of laboratory glass and glass for 

 scientific purposes. We fancy few universities and 

 schools would endorse his view, as most of them 

 have great difficulty in supplying the requirements of 

 their students. 



Prof. Boswell contributed a paper .on some recent 

 problems in geo-chemistry. The border-line of 

 chemistry and geology presents problems of the 

 greatest interest and value as regards the sources 

 and supply of raw materials for chemical manufac- 

 tures, and the necessity of finding fresh material or 

 substitutes during the war has greatlv stimulated geo- 

 chemical research. Prof. Boswell reviewed the different 

 problems created by war demands, and showed how 

 geo-chemistry has developed our home supplies of 

 materials formerly obtained from enemy countries. 



.\ short but interesting paper bv Major E. R. 

 Thomas on the work of an ammunition chemist 'n 

 the field concluded the papers directiv dealing with 

 the war. Major Thomas, with improvised appliances 

 and some Chinese coolies for labour, recovered up- 

 wards of a ton daily of KNO, and pitch from con- 

 demned ammunition. Major Thomas deserves the 

 warmest praise for setting an example of economy 

 and showing that so-called waste is reallv valuable 

 material. 



Though not directly dealing with war chemistry, a 

 paper by Drs. Lowry and Perman on the equilibrium 

 in the system ammonium nitrate — sodium chloride — 

 sodium nitrate — ammonium chloride gave the results 

 of much work conducted for war purposes. 



Several papers were contributed from H..M. Naval 

 Cordite Factory at Holton He.ath, dealing mainly with 

 industrial bacteriological problems such as the pre- 

 paration of acetone and industrial alcohol, though a 

 few of them dealt with pure organic chemistry. 

 Special jnention must be made of the paper by Dr. 

 .\. C. Thavsen, which gave a capital review of 

 different aspects of bacteriolog\- outside medicine, and 

 showed how large a field of investigation is open tr> 



