4 20 



NATURE 



[January 23, 19 19 



ing graphically by means of a jel of gas. Ii is prpf- 

 posed to replace the style by a very fine capillary. A 

 tream of air carrying ammonia >s led through the 

 ji 1 ..1 this capillar} tube and impinges on a moistened 

 paper impregnated with mercurous acetate. The 

 movements of t h<- jet, which may replace the needle 

 of a galvanometer, an- recorded in black. A. Meyer; 

 Some derivatives of isatin. 1'. <!aubert : The artificial 

 coloration of liquid crystals. The use of indophenol 

 as a colouring material presents grrnl advantages over 

 substances previously employed. Bj its means in- 

 teresting results have been obtained relating to 

 Babinet's rule and to the influence ol double refrac- 

 tion on polychroism. Ph. (ilangenud : The volcano of 

 Sancy. Its secondar) craters ami its lavas. P. 

 Lesage : The utilisation id' the curve of limits of 

 germination of seeds after soaking in solutions. If 

 seeds are immersed in alcohol there is a time bevond 

 which the seed will not germinate, and this is a func- 

 tion of the strength of the alcohol. This relation 

 between strength and time has been worked out for 

 iln' m nN of Lepidium sativUm. A possible applica- 

 tion to the selective removal of the seeds of dodder 

 is suggested. I.. I.apicque : The use of marine algse 

 I.ii feeding horses. 'The experiments were carried out 

 on L. flexicaulis, which were first dried, then washed 

 freely with the addition of a little lime or acid for 

 the removal of mucilage. The horse requires a certain 

 linn- to get accustomed to the food, about a week, and 

 then digests the alg<e completelv. For horses doing 

 no work the seaweed can be used in place of oats; 

 for light work, nutritive equilibrium was obtained 

 with 1500 grams of algse plus 500 grams of oats. A 

 horse has eaten 740 kilograms of algrc in ninety-six 

 davs without visible inconvenience. Mile. Lucienne 

 Dehorne ; False incubation in Heteronereis malgremi. 



HOOKS RECEIVED. 



Dreams and Primitive Culture. By Dr. W. H. R. 

 Risers. Pp. 28. (London : Longmans and Co.) is. 



War and Civilisation. By W. J. Perry. Pp. ^7. 

 (London: Longmans and Co.) is. 6d. net. 



The Philosophy of Mr. B*rtr*nd R*ss*ll. With an 

 Appendix of Leading Passages from Certain Other 

 Works. Edited by P.. E. B. Jourdain. Pp. 96. 

 (London: G. Allen and Inwin, Ltd.) 3s. 6d. net. 



The Origin and Evolution of Life. By Prof. H. F. 

 Osborn. Pp. xxxi + 32J. (London : (i. Bell and Sons, 

 Ltd.) 2,5s. net. 



A Manual of Elementary Zoology. By L. A. Borra- 

 daile. Second edition. Pp. xiv+616. (London: II. 

 Frowde and Hodder and Stoughton.) 16s. net. 



Forced Movements, Tropisms, and Animal Conduct. 

 B\ Dr. J. Loeb. Pp. 209. (Philadelphia and London : 

 J. B. Lippincott Co.) ion. 6d. net. 



Life and Finite Individuality. Two Symposia. 

 Edited for the Aristotelian Society, with an Intro- 

 duction, by Prof. H. Wildon Carr. Pp. 0)4. 

 (London: Williams and Norgate.) lis. net. 



\ h.aiise on Gyrostatics and Rotational Motion: 

 Theon and Applications. By Prof. A. Gray. Pp. 

 xx 4-530. (London : Macmillan andCo., Ltd.) 425.net. 



A Manual ol Geometrical Crystallography: Treating 

 Solelv of those Portions of tile Subject Useful in the 

 Identification of Minerals. By Prof. G. M. Butler. 

 Pp. viii 135. (New York: J. Wiley and Sons, 

 Inc.; London: Chapman and Hall, Ltd.) 7.".'. net. 



\ Treatise on the Sun's Radiation and Other Solar 

 Phenomena, in Continuation of the Meteorological 



Treatise on Atmospheric Circulation and Radiation, 



1015. By Prof. L. II. Bigelow. Pp. ix+385. (New 



York: I. Will \ and S-his, Inc.; London: Chapman 



and Hall, Ltd.) 23s. n< 1. 



NO. 2S6(), VOL. I02] 



DIARY OF SOCIETIES. 



THURSDAY, January -.;. 



Rovai. Institution, at 3.— Prof. J. N. Collie : Chemical Studies of 

 I '.reclaim 



Rovai. Society, at 4.30,— Admiral Sir H. Jackson and Prof. G. B. Bryan : 

 Experini- : I '• ii 1 (rating an Electrical KfiVct in Vibrating Metal-. - 

 Prof. 'I'. II. Havel.ick: Wave Ri-sisiance : Some Cases of Three-dimen- 

 sional Fluid Motion. W. S. Ahell : Chances of Loss of Merchant Ships. 

 Prof. W. M. Hicks : A Cntical Study of Spectral Series. Pan V. The 

 Spectra o! the Monatomic Gases. 



Institution of Electrical Engineers, at 6.— A. P. M. Fleming: 

 Planning a Works Research Organisation. 



FRIDAY. January 24. 



Royal Institution, at 5.30. — Temp. Lt.-Col. A. Balfour : One Side of 

 War. 



Institution of MECHANICAL Engineers, at 6. — T. T. Heaton : Klecir;. 



Welding- Henry Cave : The Development of the Oxy-acetylene Welding 



and Cutting Industry in the United Slates. — J. H. Davies : Oxy-acetylene 



Wclding.-F. Harledine: Oxy-acetylene Welding. 



MONDAY, January 27. 



Royal Geographical Society, at! 8. — Commander 'Spicer Simson. 

 D.S.O., R.N. : The Tanganyika Expedition. {Duty permitting.) 



TUESDAY, January 28. 



Royal Institution at 3. — Prof. Spenser Wilkinson: Lessons of the 

 War. 



Institution of Civil Engineers, at 5.30. — Hon. R. C. Parsons : 

 Centrifugal Pumps for Dealing with Liquids containing Solid, Fibrous, 

 and Erosive Matters. 



WEDNESDAY, January 20. 



Royal Society of Arts, at 4.30.— Dr. F. Keeble : -Food Production 

 by Intensive Cultivation. 



THURSDAY, 1 anuary 30. 



Royal Institution, at 3.— Prof. J. N. Collie : Chemical Studies of Oriental 

 Porcelain. 



Roval Society, at 4.30. — Probable Papers: Prof. J, C. McLennan and 

 R. J. Lang: An Investigation of Extreme Ultra-violet Spectra with a 

 Vacuum Grating Spectrograph. — Prof. J. C. McLennan and J. F. T. 

 Young : The Absorption Spec tra and the Ionisation Potentials of Cal- 

 cium, Strontium, and Barium.— Prof. J. C. McLennan, D. S. Ainslie, and 

 D. S.. Fuller : Vacuum Arc Spectra of various Elements in the Extreme 

 Ultra-violet.— R. C. Dearie: Emission and Absorption in the Infra-rud 

 Spectra of Mercury, Zinc, and Cadmium.— E. Wilson: The Measurement 

 of Magnetic Susceptibilities of Low Order.— Dr. F. Horton and Ann C. 

 Davies : An Experimental Determination of the Ionisation Potential for 

 Electrons in Helium. 



FRIDAY, January 31. 

 Royal Institution, at 5.30. — Prof. H. H. Turner : Giant Suns. 



SATURDAY, February 1. 

 Royai. Institution, at 3.— Prof. H. P. Allen : The Works of J. S. Bach. 



CONTENTS. page 



Diseases of Plants. By E. S. S 401 



The Double-star Worker's Vade-mecum 402 



The Science of Iron-founding 403 



Our Bookshelf 404 



Letters to the Editor: — 



Wireless Telegraphy and Solar Eclipses. — Prof. J. A. 



Fleming, F.R.S 405 



The Neglect of Biological Subjects in Education. — 



Prof. A. E. Boycott, F.R.S 405 



The Aurora Borealis of December 25, 1918. [Illus- 

 trated.) — Scriven Bolton 4°5 



Patent Law Amendment 4°5 



Natural and Artificial Camouflage 408 



Dr. H. E. J. Du Bois. By C. G. K 4°°" 



Notes 4°9 



Our Astronomical Column : — 



The Comet 1786 II 4«3 



Parallax of the Barnard Star 4'3 



The British Science Guild and its Exhibitions . . 413 



Educational Conferences 4 ! 4 



The Production of Oil from Mineral Sources. By 



Dr. F. Mollwo Perkin 416 



University and Educational Intelligence 4:7 



Societies and Academies 41S 



Books Received 4 20 



Diary of Societies 4-0 



Editorial and Publishing Offices : 



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ST. MARTIN'S STREET, LONDON, W.C.2. 



Advertisements and business letters to be addressed to the 

 Publishers. 



Editorial Communications to the Editor. 

 Telegraphic Address: Pnusis, London. 

 Telephone Number : Gekrard 8830. 



