568 



NATURE 



[October 4, 1900 



treated biologically. Mr. W. Leach, in a paper on wool-combers 

 effluents, also referred to the unsatisfactory character of the puri- 

 fication methods at present applied to the sewage. Mr. W. B. 

 Bottomley discussed the utilisation of the sewage sludge, and 

 contended that the sludge should be pressed and dried, when it 

 forms a valuable manure. Dr. Letts and Mt. R. F. Blake gave 

 a simple and accurate method for estimating the dissolved 

 oxygen in fresh water, sea water, sewage effluents, &c. 



SCIENTIFIC SERIALS. 



American Journal of Science, September.— The gas ther- 

 mometer at high temperatures, by L. Holborn and A. L. Day. 

 This is a further study of the nitrogen thermometer with 

 platinum-iridium bulb, which is superior to the porcelain bulb. 

 The correction for expansion is io° at 500°, 30° at 1000°, and 

 40° at 1150°. The authors make an elaborate comparison of 

 the gas thermometer with the thermocouples, and determine 

 anew the melting points of a number of metals. Those of 

 silver and gold are 955° and 1064° respectively — Monazite, by 

 O. A. Derby. A single granule of the mineral, no matter how 

 minute, can be securely identified by moistening it with 

 sulphuric acid on a slip of glass and burning off the sulphuric 

 acid over a spirit lamp, when the residue shows the characteristic 

 crystallisation of cerium in radiating needles or isolated crystals 

 of the shape of cucumber seeds. — The spectra of hydrogen and 

 the spectrum of aqueous vapour, by J. Trowbridge. When 

 a condenser discharge is sent through a rarefied gas confined in 

 a glass vessel, the gas cannot be considered dry, for aqueous 

 vapour is liberated from the glass. The four-line spectrum of 

 hydrogen in the solar atmosphere is an evidence of aqueous 

 vapour, and therefore of oxygen in the sun. Conclusions in 

 regard to the temperature of the stars exhibiting hydrogen 

 spectra are misleading if purely based upon conditions of 

 pressure and temperature, for electric dissociation plays a 

 determining part. X-Ray phenomena produced by a steady 

 battery current strongly suggest an electrical theory of the origin 

 of the sun's corona. — A new effect produced by stationary 

 sound-waves, by B. Davis. When a small cylinder, closed at 

 one end, is placed in the stationary sound-wave of an organ 

 pipe, it will not only arrange itself perpendicularly to the motion 

 of the wave, but will move across the wave in a direction 

 perpendicular to the stream -lines. When four such cylinders 

 are mounted in the shape of an anemometer on a needle point, 

 they rotate while the pipe is sounded. — Some interesting 

 developments of calcite crystals, by S. L. Penfield and W. E. 

 Ford. The crystals described show a great diversity of habit, 

 often on a single hand specimen, due to different methods of 

 twinning, together with peculiarities in the development of 

 certain crystal faces. Some peculiar cases of rhombohedral 

 twinning are described. — Method of measuring surface tension, 

 by J. S. Stevens. The surface tension is measured by floating 

 an iron wire on the surface of the liquid, and suspending a piece 

 of soft iron by it. The iron is pulled into a magnetising coil 

 immersed in the liquid by currents which increase until the 

 surface is broken through. 



Annalen der Physik, No. 8. — Structure, system and magnetic 

 behaviour of liquid crystals, and their mixture with solid ones, 

 by O. Lehmann. The author has succeeded in proving that all 

 the characteristics of crystallisation which the "liquid crystals" 

 described by him do not possess, cannot logically be made part 

 of the definition of a crystal. The only general characteristics 

 of crystals are that they are not isotropic, and that they possess 

 a molecular directive force which governs their shape, and the 

 manner in which their constituent particles are deposited. The 

 directive force is preserved by means of the surface tension, and 

 crystals may therefore be liquid or solid, but they cannot be 

 gaseous. Liquid crystals may be produced by depositing solid 

 crystals on the cover glass of a microscope and gently heating 

 them above the fusing point. — Generation of electricity in liquid 

 air, by H. Ebert and B. A. Hoffmann. A body suspended 

 above liquid air acquires a strong negative charge. This electri- 

 fication is due to the friction of minute particles of very cold ice 

 suspended in the air vapour. The authors constructed a kind 

 of electrifying machine by means of a tube containing a piece 

 of wire gauze through which the vapour of liquid air was 

 driven. — Spectrum of radium, by C. Runge. The author has 

 located three of Demar^ay's lines with the precision necessary to 

 distinguish them from neighbouring solar lines. The lines 

 located have wave-lengths of 4826"I4, 4682"346 and 38i4'59i 



respectively. — Influence of a spark-gap upon the generation of 

 Rontgen rays, by A. Winkelmann. The maximum gaseous 

 pressure at which X-rays can be produced may be raised by 

 introducing a spark-gap into the circuit, the best position for it 

 being next the kathode. Hydrogen yields X-rays ar greater 

 pressures than air or carbonic acid. — Fall of potential and 

 dissociation in flame gases, by E. Marx. The author proves 

 that an apparent failure of Ohm's law in flame gases is due to 

 the fact that owing to the scarcity of ions the saturation current 

 is soon attained. — Hall effect in flame gases, by the same author. 

 Owing to the great speed of the ions in flame gases, and the 

 difference in the velocities of the positive and negative ions, a 

 Hall effect is much more appreciable in flames than in electro- 

 lytes. The author demonstrates the existence of such a Hall 

 effect in the case of a flat Bunsen flame into which a fine spray 

 of a solution of some alkaline salt is blown. 



SOCIETIES AND ACADEMIES. 

 Paris. 

 Academy of Sciences, September 24. — M. Maurice Levy 

 in the chair. — Nature of the combustible gases found in the air 

 of Paris, by M, Armand Gautier. The author has shown in 

 previous papers that the ratio of carbon to hydrogen found by 

 his method of combustion in dilute mixtures of methane and 

 air is 2*4, instead of the theoretical 3. The much higher value 

 of this ratio found in the air of Paris proves that there must be 

 present gaseous substances richer in carbon than methane, such 

 as benzene vapour or its analogues. The experimental results 

 obtained are in accord with the assumption that in 100 litres of 

 Paris air there are 19 '5 c.c. of hydrogen, I2*i c.c. of methane, 

 17 c.c. of benzene vapour and 0'2 c.c. of carbon monoxide. — 

 Experiment in wireless telegraphy with the human body and 

 metallic screens, by MM. E. Guarini and F. Ponceiet. The 

 electric waves were generated by a Wimshurst influence machine 

 and were allowed to act directly upon a coherer. It was found 

 that the human body acted perfectly as a screen. — On crystallised 

 calcium aluminate, M. Em. Dufau. The crystallised aluminate is 

 obtained by heating a mixture of calcined alumina and lime in 

 an electric furnace. Its formula is CaAl204 ; it forms transparent 

 needles which do not scratch glass. — On Russian flour, by M. 

 Balland. Proximate analyses of three samples of Russian flour 

 are given. 



CONTENTS. PAGE 



A Manual of the Echinoderms. By E. A. M. . . 545 

 The Botany of Captain Cook's First Voyage. By 



W. Botting Hemsley, F.R.S 547 



Our Book Shelf:— 



Finn : " Fancy Water-Fowl." — R. L 547 



"Catalogue of Eastern and Australian Lepidoptera 

 Heterocera in the Collection of the Oxford Uni- 

 versity Museum." — W. F. K. . 548 



Egerton : " Sir Stamford Raffles : England in the Far 



East " 548 



Letters to the Editor:— 



The Teaching of Mathematics. — Oliver Heaviside, 



F.R.S 548 



The New Senate of the University of London. — 



Rev. Dr. A. Irving ... 549 



The Peopling of Australia. — ^John Mathew . . 549 



The Preservation of Big Game in Africa. By E. N. 



Buxton 550 



Notes 552 



Our Astronomical Column:— 



Ephemeris for Observations of Eros 556 



The Royal Photographic Society's Exhibition . . 556 

 The International Geological Congress. By L. 



Gentil 557 



Forthcoming Books of Science 558 



Mathematics at the British Association. By E. T. 



Whittaker .561 



Physics at the British Association. By Dr. C. H. 



Lees 562 



Astronomy at the British Association. By A. 



Fowler 565 



Chemistry at the British Association 566 



Scientific Serials 568 



Societies and Academies 568 



NO. 1614, VOL. 62] 



