71' 



NATURE 



[February 25, 191 5 



is shown to be comparable with that of hydrogen for 

 oxygen in flames. The final section describes experi- 

 ments in which the whole pressure curves, up to and 

 far beyond the attainment of maximum pressure, 

 were recorded when mixtures corresponding to 

 (i) 2H, + 0, + 4N„ (2) 2CO + 0, + 4N„ and (3) 

 CH^ + 02 + 4N2 are exploded under initial pressure of 

 about 50 atmospheres. The rates of attainment of 

 maximum pressure in each case have no direct relation 

 to the order of affinities of the various gases for 

 oxygen. — Prof. W. M. Hicks : The orbits of a charged 

 particle round an electric and magnetic nucleus. Two 

 problems are discussed — the orbits of a-particles and 

 the orbits of electrons round nuclei containing mass, 

 a definite number, n, of positive electronic charges 

 and a definite number, N, of co-axial magnetons — 

 the motion being in their equatorial planes. It is 

 found that combined systems (atoms) with a-particles 

 may exist in which the a-particle revolves in per- 

 manent connection with the nucleus, provided the 

 internal energy of the atom is greater than a certain 

 critical value, and that states of "radio-active" in- 

 stability occur in which, after a combination of long 

 duration, the a-particle is shot off to infinity. The 

 exact velocity of emission in any case depends on 

 the values of the n, N, but it is of the order of 

 magnitude of the velocity of emission of a-rays from 

 radium. In the case of electronic orbits, in addition 

 to the combined systems with internal energy less 

 than from infinity, there can exist also permanent 

 systems in which the internal energy is greater than 

 that from infinity, although less than a certain critical 

 amount, and in which again states of "radio-active" 

 instability occur of the proper order of magnitude. — 

 S. Chapman : The lunar diurnal magnetic variation 

 and its change with lunar distance. Balfour, Stewart, 

 and Schuster have developed a theory of the solar 

 diurnal magnetic variations which attributes them to 

 electric currents in the upper atmosphere, impelled 

 by electromotive forces produced by the motion of 

 the air across the earth's |>ermanent magnetic field. 

 The atmospheric conductivity is supposed to be wholly 

 or partly due to solar influence and varies with the 

 sun's hour angle. This theory apparently applies also 

 to the lunar diurnal magnetic variations which possess 

 a semi-diurnal component of constant phase, together 

 with other components the epochs of which depend on 

 the angular distance between the moon and sun ; hence, 

 when averaged over a lunation, all components save 

 the former disappear. The suggested solar influence 

 on the atmospheric conductivity is thus supported, and 

 a semi-diurnal atmospheric oscillation— such as a lunar 

 atmospheric tide — is. suggested as the source of the 

 magnetic variations. Before this theory was developed. 

 Brown (Trevandrum Observations, 1863) had found 

 that the amplitude of the 12-hour magnetic component 

 at perigee was to that at apogee in the ratio of (lunar 

 distance)-^ at the two epochs — " as in the tidal theory," 

 he briefly remarked ; but Figee (Batavian Observa- 

 tions, 1903) disputed this conclusion. The present 

 paper discusses the evidence, of this direct kind, for 

 or against a tidal origin of these magnetic variations. 

 Brown's and Figee 's data are used, together with 

 much newly computed material from other observa- 

 tories. The total hypothesis is confirmed, although on 

 account of the accidental errors affecting the minute 

 quantities under discussion, the exact law of (dis- 

 tance)-", with n = 3, is not beyond question, but if 

 n is assumed necessarily integral, its value is certainly 

 3 and not 2 or 4. — Lt.-Col. J. W. Gilford : Some tem- 

 perature refraction coefficients of optical glass. This 

 is a supplement to a paper read in 1912 in which the 

 refractive indices for 13 wave-lengths of 27 different 

 glass meltings were given by the author. To this 



NO. 2365, VOL. 94] 



table are now added similar indices for six more Jena 

 glass meltings, including those for the recent fluor 

 crown. This is followed by a table of the temperature 

 refraction coefficients for all the glass meltings dealt 

 with, and attention is directed to the abnormal co- 

 eflficients for fluor crown which is a minus quantity. 

 An attempt is then made to determine, if only approxi- 

 mately, the influence of barometric changes on the 

 refractive powers of optical glass which would seem 

 to be, similarly, a minus quantity, amounting to 

 something like six units in the sixth decimal place 

 only. 



Royal Meteorological Society, February 17. — Capt. 

 H. G. Lyons, president, in the chair. — A. E. M. 

 Geddes : Observations of the upper atmosphere at 

 Aberdeen by means of pilot balloons. These 

 observations were made at the Observatory, 

 King's College, Aberdeen, during the years 

 1912 and 1913; and in every case two theodolites 

 were used, thus securing an accurate determination 

 of the flights to a level of 3000 metres. In clear 

 weather the upward velocity of the balloon is shown 

 to be fairly uniform, but to depend on more than 

 the free lift. When clouds are present they influence 

 consider-ably this velocity, the effect differing accord- 

 ing to the nature of the cloud. The gradient wind 

 velocities and directions have been calculated and 

 compared with those actually found by observation. — 

 V. G. Anderson : Influence of weather conditions upon 

 the amounts of nitric acid and of nitrous acid in 

 the rainfall at Melbourne, Australia. The author 

 described the methods adopted and stated that the 

 results of the daily determinations from Novernber i, 

 1912, to February 28, 1914, when correlated with the 

 meteorological data for Melbourne and the isobaric 

 charts for Australia, reveal the existence of a relation 

 between weather conditions and the amounts of the 

 nitrogen acids in the rainfall. The concentration of 

 nitric acid reached a maximum in summer, a minimum 

 in winter, and an intermediate position in autumn 

 and spring. The concentration of nitrous acid reached 

 a maximum In winter and a minimum in summer. 

 Nine well-defined recurring types of rainstorms have 

 been investigated, the amounts (pounds per 1000 acres) 

 of oxidised nitrogen per day varying from i"5 in 

 the case of certain antarctic storms to 35*0 in the 

 case of intense tropical storms. 



Institution of Mining and Metallurgy, February 18. — 

 Dr. F. H. Hatch, president, In the chalr.--j. Morrow 

 Campbell : Notes on some gold occurrences in Ashanti. 

 Some 30 miles to the west of Kumasi are to be found 

 igneous rocks intruding through the schist, some of 

 which are granite, and non-auriferous. The non- 

 granite dykes, on the other hand, are mostly 

 auriferous, and the author has devoted special atten- 

 tion to three of these in his paper. All three are 

 comparatively old, and show abundant internal evi- 

 dence of the" continuance of the crustal movements to 

 which they owe their existence. These movements 

 have produced fracturing, and have resulted in the 

 formation of quartz veins traversing the igneous rock 

 in all directions, and varying in width from more 

 than a foot to mere partings. After describing in 

 detail the composition and characteristics of these 

 dykes, the author draws certain deductions. He 

 points out that in Ashanti pyrites is abundant in 

 quartz veins, and elsewhere, quite unassoclated with 

 gold, but that where arsenopyrlte occurs gold so fre- 

 quently accompanies it as to lead to the conclusion 

 that their association cannot be fortuitous. He thinks 

 It fair to conclude that the arsenopyrlte caused the 

 precipitation of the gold, and that the solution trans- 

 porting the gold contained the latter in combination 



