April 22, 1910] 



SCIENCE 



623 



The four parts of this volume which have ap- 

 peared bear the following dates, respectively: 

 August, 1904, May, 1907, April, 1908, and Au- 

 gust, 1909. 



The complete encyclopedia is to appear in 

 seven tomes, each consisting of several vol- 

 umes, probably ranging from three to five. 

 The first three tomes are to be devoted to pure 

 mathematics, while the following three are to 

 treat the applications of mathematics. The 

 seventh and last tome is to be devoted to his- 

 toric, philosophic and didactic questions. As 

 a large number of eminent French mathema- 

 ticians are engaged on the preparation of this 

 edition, its completion within a reasonable 

 number of years seems to be assured and the 

 high standard set by the dozen parts which 

 have already appeared, although they are not 

 free from serious errors, promises to be main- 

 tained in the future issues. If this is done 

 the work will be indispensable, not only 

 in the larger scientific libraries, but it will 

 also be one of the most frequently consulted 

 works in many private mathematical libraries. 

 Those who do not have easy access to a large 

 library will frequently find in this work suffi- 

 cient references to guide them safely in their 

 investigations. It is to be hoped that in this 

 way it will serve as a powerful stimulus to 

 mathematical progress in the highest and 

 widest sense. 



G. A. Miller 



University of Illinois 



Crystalline Structure and Chemical Consti- 

 tution. By A. E. H. TuTTON, D.Sc, M.A. 

 (Oxon.), F.E.S., A.R.C.S. (Lond.), Vice- 

 president of the Mineralogical Society; 

 Member of the Councils of the Chemical 

 Society and of the British Association for 

 the Advancement of Science. Cloth, 6 X 

 9, pp. viii + 200, figures 54. London, Mae- 

 millan and Co., Limited, 1910. $1.50 net. 

 This interesting volume presents in con- 

 densed and connected form the results of a 

 series of investigations in physical crystallog- 

 raphy carried out by the author during a 

 period of some twenty years, having for its 

 object the establishment upon the most accu- 



rate observational data of the exact relations 

 existing between the chemical constitution and 

 the crystalline form and properties of a series 

 of related compounds. 



These investigations consisted of three re- 

 lated parts: namely, the devising of new in- 

 struments capable of making more accurate 

 observations than had hitherto been possible 

 in this field; the perfection of methods of pre- 

 paring crystals for investigation, and the 

 actual measurements of the crystal angles and 

 other constants. 



The instruments devised, the description of 

 which occupy chapters V., VI., VII., VIII. and 

 IX., include a cutting and grinding goniom- 

 eter so arranged that the small and soft 

 artificial crystals employed could be cut and 

 polished with absolute control of the direction 

 of the artificial surface; the spectroscopic 

 monochromatic illuminator to secure for the 

 optical measurements monochromatic light of 

 any desired wave-length; the interferometer, 

 an instrument for fine measurements of length 

 ' by the interference method, employed by Tut- 

 ton as the essential optical part of the dila- 

 totneter for measuring the thermal expansion 

 of crystals and of the elasmometer for meas- 

 uring their elasticity by determining the 

 amount of bending which a plate of the crystal 

 undergoes at the center when supported near 

 its ends, under the influence of a weight ap- 

 plied at the center. By means of these highly 

 elaborate instruments the author considers 

 that he has raised the accuracy of gonio- 

 nietric measurements to the level on which 

 atomic weight determinations now stand and 

 the measurements of the physical constants 

 of crystals to the degree of accuracy of wave- 

 length determinations by the interference 

 method. 



The materials studied include some 54 salts 

 in two series; the simple anhydrous sulphates 

 and seleuates of potassium, rubidium, cassium, 

 ammonium and thallium, 10 in number; and 

 the double hydrous sulphates and selenates of 

 the above five elements with each of the metals 

 magnesium, zinc, iron, nickel, cobalt, copper, 

 manganese and cadmium, of which 44 were 

 prepared. Many crops of crystals of each salt 



