45^ 



NATURE 



[March 7, 1S95 



foumal of the Russian Ch/mical and Physical Soiiely, vol. 

 xxvi. pirts 2 to 8. — Among many valuable papere in-erted 

 in these issues, the following are especially worthy of 

 notice: — On the speed of formalim of the amines, by N. 

 Menschuikin — On the nitration of saturated hydrocarbons 

 by means of nitric acid, by M. Konovaloff. — On the solubility 

 of anhydrous calcium sulphate, by A. Potilitsin:;. — • >n the 

 isomcrisaiion of aromatic hydroearbons obtained by Friiel's 

 method, by M. Konovaloff. — On the structure of terpenes and 

 similar compounds, by G. Wagner. — On the nitration of un- 

 saturated hydrocarbons, by means of nitric acid, by M. 

 Konovaloff. — On the halogen compounds of nitrogen, by Th. 

 Selivanoff. — In the physical part : On the electric resistance 

 of bis-nuth to altemati'.f currents, by A .Sadovsky. — On the 

 valuation of electrostatic energy, by M. Schiller. — On the 

 variation in length of iron wire during magnetisation, by M. 

 Rosing. — Experiments with alteroatmg currents of high fie- 

 quenc>, by N. Slouginoff. 



Part 2 of the Journal contains also, as a supplement, the 

 first number of the Memoirs ( I'nmennik) of the Central Board 

 of Measures and Weights, which was instituted in 1893, and is 

 ]>Iaced under Prof. Mcndcleeff, who is also the editor of this 

 ]>ublication. In this first part w; nd besi es a prelace by the 

 editor, several papers of more than local interest, namely :— The 

 measurements made to compare the iron sajine of the " Com- 

 mittee of the year 1833" with various units of length, ac- 

 complished in 18S4, by MM. Glukhoff and Zaw.idski. The 

 cjmparison was also made with tlie bronze and iron yards of 

 Airy. — On the weight of a litre of air, a very elab .rate paper 

 by Prof. Mendek'eff, in which some remarks conce n ng the 

 measarements of I.educ and Lord Rayleigh, and the corrections 

 which should be introduc;diiito their nieasireaicnls.arrespecially 

 valuable. Tlie average value arrived at by Prof. Mcndeldeff 

 is, in grams, 



o = 0'l3l844..j- ± O'oooio. 



— First list of the standard measures nf weight anl length at 

 the Central Board, by Th. Zawalski. — Data fir the elaboration 

 of an instruction for verifying the weights and measires in the 

 trade estahlisnments. — Prelimina-y researches into ne* scales 

 for grain, as a means of d:terminiag the quality of the latter, 

 by Th. Selivanoff. 



SOCIETIES AND ACADEMIES. 

 London 



Royal Society, February 7.—" On the Application of the 

 Kinetic Theory to Dense Gaies." By S. H, Barbury, F.R.S. 



February 14 — "An Instrument for Cultinj, Grinding, and 

 Polishing Srction plates and Prisms of Mineralor oilier Crystals 

 .iccuralely in the dcjircd direction." By A. V.. Tution, De- 

 monstrator of Chemistry at the Royal College of .Science, 

 South Ken-ington. 



In a recent comminicition [P!ii!. Tram. 1894. Series A. 

 p. 887) the aiilior described an instrument for grinding accu- 

 rately orient.t ed seciionpla'cs and prisms of crystals of arti- 

 ficial preparations. 1 he success of that instrument is so com- 

 plete that an'ilher instrument ha> dcen devised and constructed, 

 which enables equ.illy accurately oiienlaied plates or prisms to be 

 prepared from the relatively harder crystals of natural minerals. 

 The instrument is not intended to replace the one previously 

 deiciibed, which is fully adapted for all the purposes of 

 chemical cryslallographer=, and the cost ol which is only two- 

 thirds that o( the one now describeu. It is in'ended especially 

 for the use of mineralogists, but, naturally, will serve all ihe 

 |iurpoi;$ of the smaller instrument. It is cons ructcd upon a 

 scale one-fifth larger ihan the former one as regards such parts 

 as are fundarnenlally similar, to confer greater strength. The 

 mode of supporting the outer fiied cone within which the 

 inova'il; axes rotate, the consliuciion of the circle and its axis 

 and fine adjusimeni, and of the gun-mcial axis and its counter- 

 joitlng hvcrs designed for controlling the pressure between 

 cryital and lap, as als ) of the i iner steel axis from which are 

 suspended the crystal and its centering and adjusting move- 

 ments, aie similar in principle to the torrcspondin^ arrange 

 inenti in the smaller instrument, al>hough many details are 

 .Tltered for the sake of greaicr rigidity. The same likewise 

 applies tu the goniomclrical telescope and collimator and their 



NO. 



3123, VOL. 51] 



mode o' support. The main innovations are those of a cutting 

 apparatus, ant a laigc grinding la' le capal'le of bring readily 

 furnished with any ore o( nine interchangeable grinding and 

 pibshing laps, suitable f>r use »i h cr\stals nf every drgree of 

 baldness. Four iietallic laps are jirovided, of iron, gun-metal, 

 hard white metal, and pewter respective ly, the first (or rough 

 g'i'ding with coar>e emery and I'nck oil or waier, the second 

 and th nl for fine grinding wiih (lour emery, and ihe fourih for 

 polishing with roticnsione and waier. A polishing lap of hard 

 fell, for use with putiy p iwdcr ar.d waier, an I a la|) of box- 

 wood, are supplied. Three glass laps, o le coar-ely ground, 

 another finely ground, and the third of ordinary polished plate 

 glass, arc likewise provided (or use wih ariifiL-ial cr)sals. 

 The culling apparaius is carried upon a hoiizont.il arm pivoted 

 about the back pillar ol the insirunient, in order to permi*. of 

 its removal out of the way during grinding and p 'iishing 

 operations, and further suppoitel when in use upon an adjunct 

 of the right Iront pillar. It consists o( a 4-inch disc of^ soft 

 iron, sup|ilied with diamond edge, and intended to be lubri- 

 ca'ed with brick oil, driven by an indejicndrnt driving gear 

 carried upon the arm. The supporting attachment to the fiont 

 pillar is removable "hen not required, and includes a travers- 

 ing apparatus lor directing and controlling the cutting, and a 

 safety back-spring to prevent the possilnbty o( undue pressure 

 being induced between the cu'iing di-c aid the crystal by 

 injudiciously rapid ro'ation 01 the traversing screw. In-tead 

 o( actuating the driving gear of the culling or grinding appa- 

 ratus by hand, a small electric, gas, or water mo'.or may be 

 empIo\ed. 



"On the Ratio of the Specific Heats of some Compound 

 Gases." By Dr. J. W. Capstick, Fellow of Trinity College, 

 Cambridge. 



The experiments described are a continuation of those 

 of which an account is given in the Phil. Train, vol. clxxxv. 

 p. I, Kundt's dust-figure method being used, and the ratio of 

 the specific heals correctrd (or deviation of the gas from lloyles 

 law. The results are as follows : — 



From these, and .the results given in the former paper, it 

 follows that 



(1) Replacement of one halogen by another in a conpound 



has no effect on 7. 



(2) One H in a parallin molecule may in some cases (e.g. 



ethane and propane) be replaced by CI without altering 

 7, but a second rcplacemeni always causes a (all. 



(3) Carbon and silicon can be interchanged without effect on y. 



(4) Isomeric compounds have the same y. 



(5) Using 7 10 calculate 3, 1 he ratio of the rates of increase of ill' 



traiiiolecular and Iranslational energy of the molecule OD 



a rise of temperature, we find 



fl-ti 



is constant for the 



parnllins and their monolialogcn derivatives, whence it 

 follows that for these the ratio o( the increase of mean 

 total energy to the inciense o( kinciic energy of trans- 

 lation of Ihe molecule is proportional to the number of 

 atoms in the molecule. 

 '- On some Considerations showing that Maxwell's Tlicorcm 1 

 of the I'.qual I'arlilion o( Fncigy among the Degiees ofj 



