December 15, 1898] 



NA TURE 



167 



rod of the same diameter. The different methods all point to 

 the conclusion that the ordinary formula supplies a close ap- 

 proximation to the truth only so long as the greatest diameter 

 of the cross-section is small compared to the nodal interval in 

 the rod.— A paper on the thermal properties of normal pentane, 

 by Mr. T- Rose-Innes and Dr. Sydney Young, was then read. 

 In 1894 the authors investigated the relations between the 

 temperatures, pressures and volumes of isopentane, through a 

 wide range of volume ; the results are published in the Proc. 

 Phys. Soc, xiii. pp. 602-657. It is there shown that if n and 

 /i are constants depending on the nature of the substance and on 

 the volume, the relation / = (AT -«) at constant volume holds 

 good with but small error from the largest volume (400G cub. 

 cms. per gramme) to the smallest (i'58 c.c. per g.). In the 

 neighbourhood of the critical volume (4-266 c.c), and at large 

 and very small volumes, the observed deviations are well within 

 the limits of experimental error, but at intermediate volumes 

 they are somewhat greater. As they exhibit considerable regu- 

 larity, it is a question whether they could be attributed entirely 

 to errors of experiment. In any case, the above relation may be 

 accepted as closely approximate to the truth. The present 

 paper refers to a similar investigation on pure normal pentane 

 obtained by the fractional distillation of the light distillate from 

 American petroleum. The method employed for this separation 

 is fully described in the Trans. Cliein. Soc, vol. Ixxi. p. 442, 

 1897 ; the vapour pressures, specific volumes as liquid and 

 saturated vapour, and critical constants are given in the same 

 journal, p. 446. With regard to theoretical deductions from the 

 present results, advantage is taken of the fact that a similar set 

 of experiments had already been carried out with isopentane, 

 which is an isomer of normal pentane. It was hoped that light 

 [ would be thrown on the question of the influence exerted by 

 I difference of chemical structure on the thermal properties of a 

 sub.stance. The conclusion arrived at as most probable is that 

 I the coefficients of the second power of the density in the ex- 

 pansion of / must be different for the two substances. The 

 slope of the curve obtained by plotting (at")"' against z'^i suggests 

 discontinuity somewhere about vol. 3 '4, as with isopentane. 

 '■ Mr. Lehfeldt asked whether the authors had observed any other 

 singularity or discontinuity at vol. 3'4. He also asked whether 

 the authors were satisfied with ordinary squared-paper in plotting 

 ' their curves. It ought to be possible to design a machine for 

 ' doing the work mechanically to one-fiftieth of a m.m. accuracy. 

 Mr. Appleyard said the fractionating apparatus devised by Dr. 

 ( Young was a great improvement cm older forms; it ensured that 

 there should always be sufficient and yet not too much liquid 

 at each valve-trap. He hoped that details of the tube, in its 

 I latest form, would be included in the paper. In the separation 

 ! of such a mixture as chloroform and alcohol the common method 

 1 by water-extraction was imperfect ; it was not desirable always 

 1 to convert the mixture wholly into chloroform. Ordinary 

 I fractionating tubes yielded an impure distillate in this case. 

 J Perhaps the difliculty was inherent for those two liquids. 

 ] Dr. Young's apparatus would put the question beyond doubt. 

 Dr. Young, in reply, said that the only objection to curve- 

 tracers was their cost. The curves he had obtained from his 

 experimental results were all isothermals ; he did not think 

 ' isobars would indicate anything such as Mr. Lehfeldt had sug- 

 j gested. With regard to such mixtures as chloroform and alcohol, 

 the chances of separation were difficult to predict. A distinction 

 ' might, however, be drawn between liquids partially miscible, 

 ' and liquids miscible in all proportions. Hexane (b.p. 69° C.) 



(and benzene (b.p. So° C.) for instance, were both hydrocarbons 

 miscible in all proportions, and it might be thought possible to 

 ] separate them by a fractionating apparatus. But experiment 

 J shows they cannot so be separated. If alcohol and chloroform 

 I should turn out to be miscible in all proportions, the probability 

 ] was that they could not, effectively, be fractionated ; if, on the 

 f other hand, they prove to behave like partially miscible liquids, 

 i the separation by a fractionating apparatus such as he had 

 ' described was rendered possible. — The President proposed 

 I votes of thanks to the authors, and the meeting adjourned until 

 I January 27, 1899. 



i Chemical Society, December i. — Prof. Dewar, President 

 ] in the chair. — The following papers were read : — The oxidation 

 of polyhydric alcohols in presence of iron, by H. J. H. Fenton 

 ( and H. Jackson. In presence of iron, methylic, ethylic, 

 I propylic, isopropylic and amylic alcohols are not oxidi.sed by 

 1 hydrogen peroxide ; but vigorous oxidation of ethylene glycol, 

 I glycerol, erythritol, mannitol, dulcitol and sorbitol is effected 



' NO. 1520, VOL. 59J 



by hydrogen peroxide in presence or', but> not in absence 

 of, ferrous salts. — The occurrence of hyoscyamine in the 

 Hyos<yainus )iinlkiis of India, by W. R. Dunstan and H. Brown. 

 The stem and leaves of Hyoscyaiinis muticiis contain about o'l 

 per cent, of hyo.scyamine ; the alkaloid can be extracted more 

 readily from this plant than from henbane. — The comparative 

 colour of the vapour of iodine in gases at atmospheric pressure 

 and in a vacuum, by J. Dewar. By distilling and condensing 

 iodine on a glass surface at - 180° to - 190' in vacuum test- 

 tubes or bulbs, transparent films of iodine of varying thick- 

 nesses may be obtained. On enclosing pure iodine in half-litre 

 flasks, a visible colour is imparted to the air, carbon dioxide, 

 hydrogen or oxygen with which the flask is filled at ordinary 

 temperatures ; if the flask be evacuated, the colour of the 

 atmosphere is markedly less, and this distinction remains even 

 when the flasks are heated side by side on the water-bath. 



Paris. 

 Academy of Sciences, December 5. — M. Wolf in the 

 chair. — Contribution to the theory of the .safety bicycle, by 

 M. J. Boussinesq. A mathematical investigation of the equi- 

 librium of the rider. — On the anomalous dispersion and mag- 

 netic rotatory power of certain incandescent vapours, by M. 

 Henri Becquerel. In a previous paper the author has 

 explained the unusually great rotatory power observed by 

 MM. Macaluso and Corbino for radiations from sodium 

 vapour in the immediate neighbourhood of absorption 

 bands by regarding the phenomenon as one of abnormal 

 dispersion. In the present paper experimental details are 

 given of a method of making the sodium flame act itself 

 as a prism. The spectrum from an electric arc, which 

 has passed through this flame, shows discontinuities in the 

 neighbourhood of the D-lines. The residts form a complete 

 explanation of the results of ^L^I. Macaluso and Corbino, and 

 are in agreement with the theoretical views previously put for- 

 ward by the author. — On the velocity of sound in air, by M. J. 

 VioUe. A discussion of the objections raised by M. Leduc to 

 measurements of the velocity of sound made in the open air. 

 It is shown that the presence of moisture leads to a correction 

 which is smaller than the experimental error of the measure- 

 ments. — On the synthesis of phenol from acetylene, by M. 

 Berthelot. This synthesis is of interest on account of the com- 

 paratively low temperature (200° C. ) at which it can be effected. 

 Acetylene is passed into fuming sulphuric acid, the liquid 

 diluted, and the potassium salt prepared of the acid thus formed. 

 This salt, submitted to a potash fusion at lSo° to 220° C. for 

 twenty minutes, the mass acidified and distilled ; phenol is 

 readily recognisable in the distillate. A repetition of the process 

 upon the residue in the retort yields more phenol. — Action of 

 acetylene upon the metal-ammoniums, by M. Henri Moissan. 

 The metals (sodium, potassium, lithium, and calcium) were 

 dissolved in liquid ammonia at - 40° to - 80° C. , and pure acety- 

 lene gas passed in. The residues obtained after evaporation 

 of the excess of liquid ammonia had the compositions, 

 respectively, of C,Na„.C.jHj, C.aC.C.jHo, C„Li,. C.,H.,.2NH3, 

 C.,Ca, C.,H.,, 4NH3 ; all these compounds dissociate on heating, 

 leaving the corresponding carbides, C.,Nao, C.^K.,, C.,Li.,, 

 CjCa. — The colour of calcium carbide, by M. Henri Moissan. 

 Absolutely pure calcium carbide is transparent and colourless ; 

 the presence of a minute trace of iron is sufficient to give it the 

 reddish brown colour of the material obtained by the electric 

 furnace. — On the properties of aluminium, by M. A. Ditte. 

 Aluminium is readily attacked by many chemical reagents, 

 acids, alkalies and salts ; but in many cases a protecting layer 

 of gas or oxide is formed, so that little or no action takes place 

 in cases where thermochemical data would lead to the prediction 

 of a very energetic attack. Circumstances which destroy this 

 film, le.ad to rapid solution of the aluminium. — Histology of the 

 skin, by M. L. Ranvier. A study of the fatty matter of the 

 corneal layer of epidermis in man and other mammals. — The 

 liver as a pigmented organ in the Invertebrates, by MM. A. 

 Dastre and W. Floresco. A comparison of the differences and 

 similarities of the hepatic organs in Vertebrates and Inverte- 

 brates. — On the prediction of the occultations of stars 

 by the moon, and on the calculation of terrestrial 

 Ijngitudes by means of occuliations, by M. G. Bigourdan • 

 — Numerical results obtained for the latitude of the Ob- 

 servatory of Paris by observations made on the garden 

 meridian circle, by MM. H. Renan, J. Perchot, and \V. 

 Ebert.— On the determination of gravity on the summit 



