June i8, 1903] 



NA TURE 



67 



SOCIETIES AND ACADEMIES. 



London. 



Royal Society, May 28.— "On the Theory of Refraction 

 in Gases." By George W. Walkor, M.A., A.R.C.Sc, 

 Fellow of Trinity College, Cambridge. Communicated by 

 Prof. J. J. Thomson, F.R.S. 



The present theories of refraction in gases lead to the 

 formula fi-—i = Kf{p), where N is the number of molecules 

 per unit volume, and /(/>) is a function of the frequencies 

 of the waves and independent of temperature. The 

 measured variation of fj. with temperature does not agree 

 with this formula. There are several cases where fi'-i 

 is much less than K— i, where K is the dielectric constant, 

 and in such cases we find that, although /t ^ — i is approxi- 

 mately proportional to N, K— i is nearly proportional to 

 N/^, where is the absolute temperature. 



The present theories are thus inadequate to explain the 

 actual facts. 



The view adopted in the present paper is that instead 

 of having free periods of vibrations, the molecules move 

 in constrained motion. Regarding the atom as consisting 

 of a positively charged particle united with a large number 

 of small negatively charged particles, it is supposed that 

 the negative particles roll on the surface of the positive one, 

 but do not vibrate radially. The control on transmitted 

 waves is thus the rotational energy of motion of the 

 particles, and it must be proportional to the absolute 

 temperature. 



When, by collisions or otherwise, the rotational motion 

 becomes so great that the electric attraction is overcome 

 by the centrifugal force, ionisation occurs. The frequency 

 or frequencies of rotation at which this occurs are deter- 

 mined by the electrical attractions, and are independent of 

 temperature, although, of course, the higher the tempera- 

 ture the greater will be the amount of ionisation. These 

 frequencies are regarded as corresponding to the spectral 

 lines ; this view explains the ionisation produced by ultra- 

 violet light, and also agrees with the fact that luminosity 

 is probably always connected with ionisation, e.g. the 

 characteristic lines come out in the electrical discharge 

 through the gas. 



Regarded simply, as .obstacles, the molecules must con- 

 tribute a term to /I' — i, which is proportional to N and 

 practically independent of the frequency. The final formula 

 obtained is 



fi'-i=k,N + k^^/e f{p,d), 

 where fe, and /c, are constants, and f{p,6) is a function of 

 p and d. The function is fully discussed in the paper. 



The formula is shown to be capable of accounting for all 

 the known facts connected with the dielectric constant and 

 the refractive index, while the absorption of ultra-violet 

 light and apparent absorption, due to selective reflection in 

 the infra-red, is also explained. 



Notwithstanding the very complex and varied facts in 

 air, hydrogen, carbon dioxide, ammonia and sulphur di- 

 oxide, complete numerical agreement between the measure- 

 ments of K— I and/j.-—!, as regards both absolute magni- 

 tude and dependence on pressure, temperature and 

 frequency, has been established. 



Chemical Society, June 4— Dr. W. H. Perkin, sen., 

 F.R.S., vice-president, in the chair. — ^The following papers 

 were read : — Formation of an anhydride of camphoryloxime, 

 by Dr. Lowry. This anhydride is formed when nitro- 

 camphor is boiled with concentrated hydrochloric acid. — 

 Mutarotation of glucose, as influenced by acids, bases and 

 salts, by Dr. Lowry. The mutarotaticm of glucose is 

 greatly accelerated by the presence of alkalis, less so by 

 acids, and is not influenced by the presence of salts.— The 

 solubility of dynamic isomerides, by Dr. Lowry. It is 

 shown that in some cases the determination of solubility 

 may be applied to the study of dynamic isomerides, thus the 

 solubility of />scMdo-0-bromonitrocamphor in benzene at 10° 

 increases from 23 to 93 per cent., whilst a mixture of 

 this • with its isomeride dissolves to the extent of 14 per 

 cent. — Ihe rusting of iron, by Dr. Moody. It is stated 

 that the rusting of -iron is brought about by the initial pro- 

 duction of ferrous carbonate by the action of atmospheric 

 carbon dioxide on the metal, this salt being subsequently 

 oxidised. The non-production of rust in presence of agents 

 which destroy hydrogen peroxide • is regarded as due, not 



^o- 1755. VOL. 68] 



as Dunstan suggested, to the destruction of hydrogen 

 peioxide, but to the insolubility of carbon dioxide in solu- 

 tions of these substances. In the discussion it was pointed 

 out that the presence of impurities in the iron or in the 

 reagents employed would materially affect the production 

 of rust bv inducing electrolytic changes, and that Dunstan 

 had already pointed out that carbon dioxide exercised an 

 accelerating influence in the production of iron rust.— - 

 Iminoethers corresponding with ortho-substituted benzenoid 

 amides, by G. D. Lander and F. T. Jewson. The authors 

 find that they get better yields of iminoethers by alkylation 

 in an ethereal solution than in an alcoholic one, but even 

 there nitriles are formed. They also find that whilst 

 o-toluamide gives a yield of only 13-6 per cent., 

 /)-toluamide gives 70 per cent, of iminoether. — The 

 hydrolysis of ethyl mandelate by lipase, by H. D. Dakin. 

 It is shown that i-ethyl mandelate is unequally hydrolysed 

 by this enzyme, the product being J-mandelic acid. — Iso- 

 meric change in benzene derivatives. The conditions in- 

 fluencing the interchange of halogen and hydroxyl in 

 benzene diazonium hydroxides, by Dr. Orton. — The syn- 

 thesis of ao7-trimethylglutaric acid and its derivatives, 

 by Dr. W. H. Perkin, jun., and Miss A. E. Smith.— 

 Hexamethyleneoctocarboxylic acid and the cis- and trans- 

 modifications of hexamethylenetetracarboxylic acid, by 

 Messrs. Gregory and Perkin. — The bases contained in 

 Scottish shale oil, part ii., by Messrs. Garrett and Smythe. 

 — A direct method for determining latent heat of evapor- 

 ation, by Dr. J. Campbell Brown. The weight of liquid 

 evaporated by a determinate amount of heat, applied at 

 the boiling temperature of the substance, is determined in 

 a special apparatus. — The four isomeric hydrindamine-d- 

 chlorocamphorsulphonates and isomeric compounds of the 

 type NRiRjH,, by Dr. Kipping:. The isolation of the 

 isomeric hydrindamine salts referred to in the previous paper 

 affords conclusive evidence of the occurrence of isomerism 

 among quinquevalent nitrogen compounds of this type. 

 The author accounts for this isomerism by the assumption 

 that the five valencies of the nitrogen atom are directed 

 from the centre to the angles of a square pyramid. 

 Paris. 

 Academy of Sciences, June 8. — M. Albert Gaudry in 

 the chair. — On a new general relation between electro- 

 motive forces of saline solutions, by M. Berthelot. If an 

 element formed by two saline solutions separated by a 

 porous partition A and B has an electromotive force E, the 

 element A+AB, formed by the two solutions A and AB, 

 with electromotive force «i, and the element B and AB, 

 with electromotive force «,, then the relation E = «i + «2 is 

 found to hold good. The relation concerning the union of 

 acids and bases, established by earlier experimenters, is a 

 corollary to this more general case. — The formation of 

 alcohol in the fermentation of plant juices containing 

 sugar, by M. Armand Gautier. An atteinpt to distinguish 

 analytically between a naturally fermented wine and a 

 liquid artificially fortified with alcohol. Attention was paid 

 especially to the various forms in which nitrogen compounds 

 were present ; estimations of glycerol and acidity were also 

 made. It was found that the best characteristics of a really 

 fermented liquid were the amount of volatile acid and the com- 

 plete absence of ammoniacal nitrogen. — On the propagation 

 of waves in a perfectly elastic medium affected by finite de- 

 formations, by M. P. Duhem. — Prof. Lorentz was nomin- 

 ated a correspondant for the section of physics in the place 

 of M. Amagat. — On the results obtained by cannonading 

 against hail. storms, by M. E. Vidai. — On the integrals of 

 the equation s = f{x, y, z, p, q), by M. E. Goursat. — On 

 differential equations of the third order which admit of a 

 continuous group of transformations, by M. A. BouianKer. 

 — The motion of a solid in a gaseous medium, by M. L. 

 Jacob. — An examination of the conditions which deter- 

 mine the sign and the magnitude of electrical osmosis and 

 of electrification by contact, by M. Jean Porrin, Electrical 

 osmosis is intense only for ionising liquids ; thus a marked 

 effect was produced with water, methyl, ethyl, and propyl 

 alcohols, acetone and nitrobenzene, but was absent with 

 benzene, ether and turpentine. — On the external thermal 

 cnductivity of silver wires plunged in water, by M. E. 

 Ragrovsky. The wires were heated electrically, and a 

 steady current of water passed at a measured rate through 

 the tube surrounding the wire, observations being made 



