45

Notes and News

International Union of Crystallography its Chairman and General Secretary at a meeting of that Acta CrystaUographica. The machinery by which this body held in Paris on 1 and 2 July 1947. On l0 October journal was established is reported in the Editorial Preface 1947 Great Britain, through the Royal Society, formally in this issue. Its production at a moderate price intended adhered to the Union. Adhesion is known to be under to secure wide distribution and ready accessibility to consideration in other countries. workers throughout the world would not have been The officers of the Union are: possible, however, without the assurance of financial Chairman: guarantees, and it is appropriate to record here the P. P. EWALD gratitude of the Union to the undermentioned Research Executive Committee: Associations, industrial firms and other organizations M. J. BUERGER C. MAUOUIN whose generous support has enabled the journal to be D. HARKER A.V. SHUBNIKOV launched free from financial embarrassment. J. A. A. KETELAAR W.H. TAYLOR *Albright and Wilson Ltd., , . General Secretary: Aluminium Company of America. *Associated Electrical Industries Ltd., London, England. R. C. EVANS, Automatic Telephone and Electric Co. Ltd., Liverpool, England. Crystallographic Laboratory, Bell Telephone Laboratories Inc., New York, N.Y., U.S.A. Cavendish Laboratory, *Boots Pure Drug Co. Ltd., Nottingham, England. Cambridge, England. Bristol Aeroplane Co. Ltd., Bristol, England. *British Ahuninium Co. Ltd. Copies of the Statutes and By-Laws of the Union may *British Celanese Ltd. *British Cotton Industry Research Association. be had from the General Secretary on application. The British Electrical and Allied Industries Research Association. full text will be published in an early issue of this journal. British Insulated Callender's Cables Ltd. *British Iron and Steel Research Association. *British Jute Trade Research Association. International Tables. A Sub-Committee of tile Union British Leather Manufacturers' Research Association. has been set up to consider the production of a second *British Non-Ferrous Metals Research Association. edition of the International Tables for the Determination of British Oxygen Co. Ltd. The members of this Sub-Committee *British Shipbuilding Research Association. Crystal Structures. *British Titan Products Co. Ltd. are: C. HERMAN:N A.L. PATTERSON *De Havilland Aircraft Co. Ltd., Hatfield, England. *Distillers Co. Ltd., Epsom, England. KATHLEEN LO~SDALE J.M. ROBERTSON Dew Chemical Co., Midland, Mich., U.S.A. W. NOWACKI J. WYART * Rubber Co. Ltd., London, England. *Electrical and Musical Industries Ltd., Hayes, England. Secretary : *English Electric Co. Ltd. M. J. BUERGER, *Essex Acre Ltd., Gravesend, England. Department of Geology, *Ferranti Ltd., London, England. *Fine Spinners and Doublers Ltd., , England. Massachusetts Institute of Technology, General Electric Co. Ltd., Wembley, England. Cambridge 39, Hercules Powder Co., Wilmington, Del., U.S.A. Massachusetts, U.S.A. Adam Hilger Ltd., London, England. *Imperial Chemical Industries Ltd., London, England. Institute of Physics, London, England. Structure Reports. A further Sub-Committee of the *Lever Bros. and Unilever Ltd., London, England. Union has been formed to consider the publication of *May and Baker Ltd., Dagenham, England. periodic Structure Reports analogous to the former German Machlett Laboratories Inc., Springdale, Conn., U.S.A. The members of this Sub-Committee are: Owens-Illinois Glass Co., Toledo, Ohio, U.S.A. Strukturbericht. * Bros. Ltd., St Helens, England. J. D. BERNAL R. W. G. WYCKOFF Proctor and Gamble Co., Cincinnati, Ohio, U.S.A. *Rolls Royce Ltd., Derby, England. J. WYART Royal Society, London, England. Secretary : *Standard Telephones and Cables Ltd., London, England. Swift and Co., Chicago, Ill., U.S.A. P. P. EWALD, *Telegraph Construction and Maintenance Co Ltd., London, The Queen's University, England. , John Thompson Engineering Co. Ltd., Wolverhampton, Northern Ireland England. *Tootal Broadhurst Leo Co. Ltd., Manchester, England. U.N.E.S.C.O. General Assembly and International Congress. At the * Ltd., Rothorham, England. invitation of the American Society for X-ray and Elec- *-Armstrongs Ltd., London, England. tron Diffraction and of the Crystallographic Society of * These organizations have generously undertaken to con- America, the First General Assembly and International tinue their support, if necessary, for a period of five years. Congress of the Union will be held at Harvard University, The Union. The International Union of Crystallography Cambridge, Mass., U.S.A. from 28 July to 3 August 1948. was formally recognized by the International Council of Delegates to the General Assembly will be nominated Scientific Unions on 7 April 1947 and was represented by by the National Academies of countries adhering to the 46 NOTES AND NEWS

Union, but all crystallographers are cordially invited to quoted by Birgo in the 1941 volume of the Physical Society'~ attend the International Congress. Those outside of the Reports on Progress in Physics, should be used in conjunction with these wave-lengths. In particular, density p is given by U.S.A. expecting to be present are requested to inform the equation the General Secretary at a very early date in order that p= 1.66020 ZA/V, detailed planning may proceed without delay; those will- where EA is the sum of the atomic weights of the atoms in tlm ing to contribute papers should at the same time forward unit cell, and V is the volume of the unit cell in A s. details for consideration by the Programme Committee. Absorption Crystallographers in the U.S.A. will receive separate Ka x K% K~ K flx edge notification from the A.S.X.R.E.D. or the Crystallo- Cr 2-289 62 2.293 52 2.290 9 2-084 79 2.070 1 graphic Society of America. It will unfortunately not Mn 2.101 74 2.105 70 2.103 1 1-910 16 1.895 4 be possible for the Union to provide funds to assist Fe 1.935 97 1-939 91 1.937 3 1.756 54 1-742 9 Co 1.788 90 1.792 79 1.790 2 1.620 73 1.607 2 delegates in attending the Congress and crystallographers Ni 1-657 83 1.661 68 1.659 1 1.500 08 1.486 9 should therefore make their own arrangements in this Cu 1-540 50 1-544 34 1-541 8 1.392 17 1.380 2 matter. Zn 1.435 10 1.438 94 1-436 4 1.295 20 1.283 1 Me 0-709 26 0.713 54 0.710 7 0.632 25 0.619 7 kX and Angstr6m units Rh 0.613 26 0.617 62 0.614 7 0.545 59 0.534 1 lad 0.585 45 0.589 82 0.586 9 0.520 52 0.509 0 The following letter is reprinted by permission from J. Sci. Ag 0.559 41 0.563 81 0.560 9 0.497 01 0.485 5 Instrum. (1947), 24, 27: It is recommended that in any published work the values of At the annual conference of the X-ray Analysis Group of the the wave-lengths used should be explicitly stated. Institute of Physics in July 1946 it was announced that agree- ment had boon reached concerning the factor for converting W. L. BRAGG, Chairman, measurements in kX units to ,3~gstr6m units. The factor X-ray Analysis Group of the Institute of Physics agreed upon, after consultation with the American Society for Cavendish Laboratory, X-ray and Electron Diffraction and Prof. Siegbahn was 1-00202. Cambridge, England This factor is probably correct to 0.003 %. Since wave-lengths in X-units have boon measured to an accuracy of 0.001%, the wave-lengths in Angstr6m units can be taken as accurate to Authors of papers intended for publication in Acta 0.004 % in general. Crystallographica are requested to express cell dimensions The following is a list of values of wave-lengths in Angstr6m and related quantities in Angstr6m units and, when the units of certain omission lines and absorption edges in common use. The column headed Ka gives the mean value of Ka~ and accuracy of the work justifies the distinction between these K~ 2, K~ 1 being allowed twice the weight of Kay. and ki units, to avoid all possible confusion by quoting Current values of the physical constants, such as those also explicitly the wave-length of the radiation used.

Book Reviews

Works intended for notice in this column should be sent direct to the Editor (P. P. Ewald, The Queen's University, Belfast, Northern Ireland). As far as practicable books will be reviewed in a country different from that of publication.

Grundlagen der allgemeinen Mineralogie und classes are given, only Schoenflies symbols are used. Most Kristallchemie. By F. MACHATSCHKI. Pp. vii + 209, teachers of the subject will regret his missing the chance of with 151 figs. Springer Verlag, Vienna, 1946. Price, introducing students as soon as possible to the simpler and 16 schillings; $2.80. more elegant Hermann-Mauguin nomenclature. F.A. BANNISTER Professor Machatschki, who now occupies the chair of British Museum (Natural History), mineralogy in the University of Vienna, has been asso- London, S.W. 7, ciated with the development of the X-ray analysis of the England. crystal structure of minerals since 1927. For a time he joined the group of brilliant research workers who formed Die Bewegungsgruppen der Kristallographi¢. By the Bragg school in Manchester and first suggested in out- J. J. BURCKHARDT. Pp. 189, with 56 figs. Verlag line the framework of the felspar structures. Since then Birkh/~user, Basel. Price, 29 Swiss francs. he has produced an unceasing flow of papers ranging over This book represents the result of a twenty-year investi- the whole field of mineral chemistry. gation of the intrinsic mathematical theory of the crystallo- The book now under review is a well-written, clearly graphic groups. In the words of Burckhardt : 'Mich heute printed, and adequately illustrated class-book suitable for yon dieser Arbeit zu trennen, f/~llt mir schwer: w/~hrend teaching elementary students. It is divided into three zwanzig Jahren war sie mein Stab und meine Stfitze main sections; crystallography, crystal physics, and zugleich.' The basic point of view of the book resembles crystal chemistry, and concludes with brief accounts of the closely that adopted by the reviewer in a series of articles genesis of crystals, etch figures and pseudomorphs. Parti- in the Zeitschrift fi2r Kristallographie in the early 1930's cularly commendable are the introductions to crystal under the title 'A Matrix-Algebraic Development of the optics and crystal chemistry. The author's method of Crystallographic Groups'. That is, an attempt is made to tabulating the thirty-two crystal classes, however, is less abstract the process ofderixdng the crystallographic groups in keeping with the up-to-date treatment in the rest of from the somewhat earth-bound tactics of straight-edge the book. Although two systems of naming the crystal and compass geometry used by the group of theoretical