November 17, 1910] 



NATURE 



69 



Iioff, ZoUner, Secchi, &c. Then at some length the 



circular refraction and anomalous dispersion theories 



by Schmidt and Julius respectively are discussed. 



The temperature of the sun comes next under review, 



allowed by a chapter on the dynamic and thermal 



quilibrium of the sun. Lastly, the electromagnetic 



held of the sun and the theories concerning the corona 



are taken in hand, and the views of Schuster, Bige- 



low, Deslandres, Ebert, Nordmann, Arrhenius, &c., 



ire contrasted. This chapter also includes an account 



t Hale's work on the magnetic field in sun-spots, and 



recent researches carried out at Meudon on the high 



level strata of the solar atmosphere. 



The text is well illustrated with numerous repro- 

 ductions from recent solar researches, and the volume 

 contains good bibliographical author and subject 

 indices. 



(2) Prof. Pringsheim's book is the outcome of a set 

 '^f lectures which extended over a series of years at 

 le Berlin Universit\'. These lectures were not re- 

 >tricted to astronomical students only, so that the 

 subject was dealt with in a little more popular manner 

 than otherwise would probably have been the case. 



The twelve lectures which form the subject of this 

 volume comprise a comprehensive sur\ev of the past 

 and present views relative to the physics of the. sun, 

 and the author has managed to include a great deal of 

 material in these lectures. The information has been 

 brought well up to date, and the monochromatic 

 work accomplished by the aid of the spectroheliograph 

 in the hands of Deslandres and Hale has been 

 thoroughly dealt with, and forms a valuable chapter. 

 The volume is well illustrated, contains a great 

 number of references, and is accompanied bv useful 

 subject and name indices. It will be found a service- 

 able book for students and a good readable volume for 

 those who wish to become acquainted with the pro- 

 ress in our knowledge of the physics of the sun. 



-OME ASPECTS OF PHYSICAL CHEMISTRY. 

 II The Elements. Speculations as to their Nature 

 atid Origin. By Sir William A. Tilden, F.R.S. 

 Pp. xi+139. (London and New York: Harper 

 and Brothers, 1910.) Price 25. 6d. net. 

 ^i) The Relations between Chemical Constitution and 

 ^Some Physical Properties. (Text-Books of Physical 

 ^cience. Edited by Sir William Ramsav.) By 

 prof. Samuel Smiles. Pp. xiv + 583. (London: 

 |Longmans, Green and Co., 1910.) Price 145. 

 Physical Chemistry. Its Bearing on Biology and 

 Medicine. By Prof. James C. Philip. Pp. vii + 

 ^^2. (London : Edward .Arnold, 1910.) Price 

 7s. 6d. net. 



T^HE discovery of radio-activity has, by the 

 introduction of a new idea,' reawakened in- 

 terest in many outstanding problems of physical 

 saence. Prominent among these is the fascinating 

 question of the nature and origin of the elements. 

 Chemists with the periodic table of Mendeleeff before 

 them, in spite of the warnings of its author, have 

 been unable to resist the idea that some close genetic 

 NO. 2142, VOL. 85] 



relation exists between the different elements of the 

 nine groups of which the table consists, certainly 

 along the vertical lines and probably also along the 

 horizontal series. As to the nature of this relation- 

 ship, nothing very definite was known or even imagined 

 beyond the fact that it was accompanied by increase 

 in atomic mass, and the probability that it was the 

 result of condensation of some primal matter or 

 protyle, under the influence, of changing conditions, 

 of which temperature was possibly one of the chief 

 factors. 



(i) The effect of recent work on the views enter- 

 tained by chemists on this question forms the subject- 

 matter of the latter portion of Sir \Mlliam Tilden 's 

 book, the former half being devoted to a brief and 

 clear exposition of the ideas which led to 'the formula- 

 tion of the periodic law. The interesting account given 

 of the various theories of the evolution and constitu- 

 ! tion of the elements which have recently been proposed 

 culminates in a tentative and most suggestive genea- 

 logical table of the elements, which cannot fail to 

 arrest the attention of all chemists. The author 

 favours the idea that the elements of the seven chief 

 vertical groups (with exception of the families headed 

 by copper, chromium, and manganese) are directly 

 "descended" from the seven elements from sodium 

 to chlorine, the members of the odd and even series 

 forming separate families with a common ancestor. 

 The remaining elements (Group 8 and the exceptions 

 just mentioned) are more or less directly descended 

 from iron, which itself is placed in genetic relation 

 with aluminium. The elements sodium to chlorine 

 are direct de.scendants of the corresponding elements 

 of lower atomic weight, lithium to fluorine, and these 

 are themselves formed by the condensation of vary- 

 ing proportions of the two primal constituents of all 

 matter, positive and negative protyle, as to the nature 

 of which nothing is known. It is, moreover, by the 

 addition of further amounts of these two primal sub- 

 stances that one element is derived from another 

 of lower atomic weight. 



Hydrogen is ^ progenitor of lithium, and a new 

 unknown element, of atomic weight 3, is postulated 

 as a precursor of fluorine. The elements of the zero, 

 group (the helium gases) are supposed to be by- 

 products of the disintegration of elements of high 

 atomic weight, possibly long extinct. In this con- 

 nection it may be noted that the radium emanation 

 is stated to be wholly converted into helium, a con- 

 ception at variance with the generally received idea. 

 Such a scheme, in the nature of things, teems 

 with doubtful points, and the author is to be con- 

 gratulated on his courage in exposing his ideas to 

 the shafts of criticism which are sure to be winged 

 against them. His table, however, undoubtedly ex- 

 presses much that has been vaguely in the minds of 

 many chemists, and removes some of the chief diffi- 

 culties inherent in the classification of the elements 

 in the strict order of their atomic weights. Where 

 it appears to be deficient is in the expression of the 

 relations between the members of the horizontal 

 series. It must also be remembered that the onlv 

 positive evidence of genetic relationship at present 



