ii8 



NA TURE 



[November 30, 1893 



manner from that in the case of a constant current. The 

 amounts of heat developed in wires of iron, German silver, 

 brass, and copper 6 cm. long and of o'OlS cm. radius, were in 

 the proportion of 105 : I 75 : I : I, the last being probably a 

 little too large. The branching of the oscillations is only af- 

 fected by the self-induction of the wires, not by their resistance. 

 — The emission of hot gases, by F. Paschen (see p. 82). — A 

 simple method of testing the conductivity of dielectric liquids, 

 '^i K. R. Koch. The apparatus used for this method is a modi- 

 fied Dewar capillary electrometer, in which a drop of the 

 subsLance to be examined takes the place of the drop of sul- 

 phuric acid usually employed for determining differences of 

 potential. Any electrolytic polarisation is indicated by a 

 movement of the drop of liquid, which should not be more than 

 o'5 mm. Jong. The conductivity of various dielectrics has thus 

 been studied, and has in many cases been found to be due to 

 impurities. Benzol, carefully cleaned and freed from moisture, 

 ceased to show any polarisation. — On the magnetic susceptibility 

 of oxygen, by R. Hennig (see Notes). 



SOCIETIES AND ACADEMIES. 



London. 



Chemical Society, November 2. — Dr. Armstrong, Pre- 

 sident, in the chair. — The following papers were read : — The 

 action of bromine on azobenzene : a correction, by H. E. Arm- 

 strong. The colourless bromination product of azobenzene is 

 tetrabromobenzidine, and not a tetrabromazohenzene, as stated 

 by Werigo. — The origin of colour. X. Coloured hydrocarbons, 

 by H. E. Armstrong. — The formation of the hydrocarbon 

 "truxene" from phenylpropionic acid and from hydrindone, by 

 F. S. Kipping. On heating hydrindone with dehydrating 

 agents, a hydrocarbon of the constitution 



C«H4 . C : C . CH2 



C Ho . C : C . CgHi 

 is formed ; it is identical with truxene, to which the molecular 

 formula Cj-Hjg has been erroneously assigned by Liebermann 

 and Bergami. Further, Gabriel and Michael's '* tribenzoylene- 

 benzene " in all probability has the molecular formula CjgHgO^ 

 instead of C27H]o03, as has previously been supposed. — 

 The action of alummium chloride on heptylic chloride, by 

 F. S. Kipping. A crystalline ketone of the composition 

 C]4H„(,0, is formed by the interaction of heptylic chloride and 

 aluminium chloride. — The inertness of quicklime. II. The 

 interaction of chlorine and lime, by V. H. Veley. Dry chlorine 

 has no appreciable action on quicklime below 300° ; above this 

 temperature, a partial replacement of oxygen by chlorine occurs. 

 — Note on hyponitrites, by D. H. Jackson. No hyponitrite is 

 formed during the reduction of sodium nitrate with aluminium 

 or barium amalgam. Diver's process for preparing hyponitrites 

 gives the best results when a weak sodium amalgam is employed, 

 and when the action proceeds at a low temperature. — The inter- 

 action of hydrogen chloride and potassium chlorate, by W. H. 

 Pendlebury and Mrs. McKillop. The authors have determined 

 the amounts of oxidising gases removed, during successive 

 periods of time, from an aqueous solution of hydrogen chloride 

 and potassium chlorate by a current of air. The action of sun- 

 light on the solution materially increases the quantity of oxidising 

 gas carried away by the air current. — The formation of indoxazen 

 derivatives, by W. A. Bone. The author has studied the action 

 of alkalis on orthochloronitrobenzaldoxime with the object of 

 preparing nitrindoxazen ; in place of this substance, however, 

 the isomeric 1:2:5 nitrosalicylonitril was isolated, molecular 

 change having occurred during the interaction. A number of 

 new nitro-derivatives were obtained. — The interaction of benzyl- 

 amine and phenacyl bromide. Synthesis of piazine derivatives, 

 by A. T. Mason and G. Winder. Phenacyl bromide and 

 benzylamine readily interact with formation ol ihe hydrobromides 

 ofmonophenacylbenzylamine, Ph . CO. CHj. NH . CHoPhand. 

 diphenacylbenzylamine (Ph . Co . CH2)2N , CHg . Ph ; on liber- 

 atmg the bases, molecular changes occur. In the case of the 

 monophenacyl-derivative, i . 4-dibenzyl-2 : 5-diphenylpiazine di- 

 hydride is obtained ; when this substance is heated to the 

 boiling-point, it yields toluene and 2 : 5diphenylpiazine. 



CH-NCPh 



CPhN-CH 



A number of other piazine derivatives are also described. — The 

 interaction of quinones and metanitraniline and nitroparatolu- 



NO. 1257. VOL. 49] 



idine : a preliminary note, by J. Leicester. The author de- 

 scribes a number of condensation products of quinones with 

 w-nitraniline and nitro-/-toluidine. — Preparation of o-;3-di- 

 phenylindoles from benzoin and primary benzenoid amines, by 

 F, R. Japp and T. S. Murray. A mixture of benzoin, aniline, 

 and zinc chloride yields o-/3-diphenylindole, in accordance with 

 the following equation 



Ph . NH„ -f Ph . CO . CH(OH)Ph 



= CgH / ^CPh„ -f 2H2O. 



\nh/ 



New substituted indoles may be prepared by the employment of 

 other aromatic amines in place of aniline. 



Mathematical Society, November 9.— A. B. Kempe, 

 F.R. S., President, in the chair. — The resolution for the incor- 

 poration of the Society, and the list of names as new Council for 

 the session 1893-4 (see Nature, vol. xlviii. p. 619), were car- 

 ried unanimously. — The President gave a brief account of the 

 life and work of the late W. S. B. Woolhouse, and then 

 accompanied the presentation of the De Morgan medal, which 

 had been awarded by the Council in June last to Prof. F. 

 Klein, of Gottingen, with an outline sketch of the grounds of 

 the award. Prof. Greenhill, F.R.S., and Dr. Forsyth, F.R.S., 

 who had been deputed by Prof. Klein, in his unavoidable 

 absence, to receive the medal, suitably acknowledged the gift. 

 The following communications were made : — A mechanical 

 solution of the problem of tethering a horse to the circumfer- 

 ence of a circular field, so as to graze over an «"' part of it, 

 by Prof. L. J. Rogers. (The solution turned on a property of the 

 cycloid). — The stability of certain vortex motions, by A. E. H. 

 Love. The paper contains investigations of the steady motion 

 and small oscillations of Kirchhoff's elliptic vortex, which 

 rotates uniformly in the midst of an infinite mass of liquid, and 

 of Hill's elliptic vortex, which rotates uniformly in the midst 

 of a mass of liquid filling a confocal rigid envelope, the enve- 

 lope rotating with the same angular velocity. It is proved that 

 Kirchhoff's vortex is stable for all modes of oscillation in which 

 the boundary ceases to be elliptic, provided the major axis is 

 less than three times the minor axis. It is also proved that if 

 the boundary is any ellipse, the vortex rotates steadily with 

 angular velocity suitable to its eccentricity, and that it is im- 

 possible for it to change form and remain elliptic. The charac- 

 teristics of the various modes of oscillation are made out, viz. 

 it is shown that for each mode there is a definite number of 

 wave-lengths of a simple harmonic disturbance in the circum- 

 ference, prorided the amplitude of the disturbance is measured 

 by the ratio of the normal displacement of a point in the bound- 

 ary to the central perpendicular on the tangent at the point. 

 The general period equations are obtained, and it is shown in 

 particular that Hill's vortex is always stable for elliptic dis- 

 placements of the boundary of the vortex, the frequency for 

 such displacements tending to zero when the vortex degenerates 

 into a Kirchhoff's vortex by indefinite expansion of the external 

 boundary of the liquid, thus verifying the results found in the 

 more special case. It is also verified that the vortex sheet, 

 which is another degenerate Hill's vortex, is always unstable 

 for the more complex types of disturbance. Messrs. Hill, 

 Basset, Greenhill, and Bryan spoke upon the paper. — Cyclo- 

 tomic quartics, by Prof. G. B. Mathews. — On the application 

 of elliptic funciflons to the curve of intersection of two quadrics, 

 by J. E. Campbell. — Note on the theory of groups of finite 

 order, by Prof. W. Burnside, F. R.S. The only quite general 

 theorem at present known concerning the structure of a group 

 (of finite order) is the following, due to Herr Sylow : " If/" is 

 the highest power of a prime / that divides the order of a group, , 

 the group contains a single conjugate set of sub-groups of order t 

 /", and the number of such sub-groups is congruent to unity, , 

 modulus p." In the theory of groups of finite order, and 

 especially in considering the possible structure of a group of 

 given order, this theorem is fundamental. From its enuncia- 

 tion it is clearly independent of the form in which the group i| 

 may be represented. The only published proofs of it, to the | 

 best of the author's knowledge, are the original proof by Herr ij 

 Sylow {Math. Ami. vol. v.), and a proof given by Herr Netto 

 in his " Substitutionentheorie." These both depend essentially \ 

 on the representation of the group as a group of substitutions, 

 and also on the conception of transitivity in connection with 

 this form of representation. A proof of the theorem is given in 

 the first of these notes, which is as fundamental in conception as 



