December 22, 1921] 



NATURE 



527 



making a very interesting and instructive \oluine. 

 We think tliat the illustrations, which are many 

 and various, reach a rather higher standard of 

 excellence than that to which we have been accus- 

 tomed. The editor tells us that undoubtedly, in 

 time, all text-composing for printing will be done 

 by a photo-mechanical process, and that this matter 

 is still being worked at and progress made. Collo- 

 type, which many used to suppose to be too trouble- 

 some to work in this coimtry, because of the vagaries 

 of the climate, appears to be gaining in favour, and 

 can be combined with offset methods to considerable 

 advantage. An example of such a combination is 

 given in a coloured collotype of Messrs. Howard and 

 Jones. The history of the Print Society by Mr. 

 M. F. Whittington, with offset examples, will be 

 appreciated by many artists and collectors who 

 favour etching as a means of expression. Mr. 

 Gamble, in his "Review," refers to the neglect of 

 inventors and inventions, and we would heartily 

 second his desire that such neglect might be avoided. 

 He is, however, unfortunate in one of his examples 

 — namely, the " Electrical Inkless Printing " pro- 

 cess, which was shown some five-and -twenty years 

 ago by the late Mr. Friese Greene. Mr. Gamble 

 savs that Mr. Greene " was unable to find the neces- 

 sary financial support, and the process died out of 

 recollection." The weak point of that method was 

 diagnosed in a moment by those who were well 

 grounded in scientific principles. The paper wis 

 sensitised all over (essentially by a salt of man- 

 ganese), but the sensitive material unused was not, 

 and probably could not be economically, removed. 

 The present writer has specimens that were then pro- 

 duced. For years they have been covered with a 

 dirty brown stain, often in smudges, and the stain- 

 ing has extended to the envelope that contains them. 



C. J. 



Vorlesungen i'lher die Theorie der Wcirmestrah- 

 lung. By Prof. Max Planck. Vierte, Ahermals 

 Umgearheitete Auflage. Pp. xi -1-224. (Leip- 

 zig-: Johann Ambrosius Barth, 1921.) 

 36 marks. 

 This work has now gone through four editions, 

 and it remains the standard book on the theon,- 

 of radiation. The earlier parts, dealing with the 

 classical theory, are practically unaltered, and 

 constitute still far the most thorough introduction 

 which a student could have into the rather diffi- 

 cult ideas of the theory. The later part differs 

 from the earlier editions ver\' considerably. In 

 the first and second editions the end of the book 

 contained a good deal of rather arid discussion 

 of the radiation problem from several only 

 slightly different points of view. All this has now- 

 been replaced by a very interesting development 

 of the quantum theory, in particular of those 

 branches, including radiation, which concern tem- 

 perature problems. The discussion from the point 

 of view of entropy is very complete, except for 

 the lack of an explanation of why it is right first 

 to define entropy in terms of probability, and then 

 to re-define probability — the so-called thermo- 



NO. 2721, VOL. 108] 



dynamic probability — so as to derive from it the 

 " absolute " entropy. Apart from this question 

 of the arbitrary constant in the entropy, there is 

 a very clear account of Planck's more recent work 

 on the equation of state of gases. 



Der Entropologische Gottesbeweis : Die physikcd- 

 ische Entivicklung des Entropieprinzips , seine 

 philosophische iind apologetische Bedeuiung. 

 By Dr. Josef Schnippenkotter. Pp. 109. 

 (Bonn : A. Marcus and E. Webers Verlag, 

 1920.) 15 marks. 



To anyone familiar with modern physics it is a 

 frequent occurrence to observe encroachments of 

 the second law of thermodynamics on more and 

 yet more branches of science ; but it comes at first 

 as rather a surprise that it covers a still wider 

 field and has also an application in theology. Yet 

 the connection is not so remote as appears at first 

 sight, for alone of all the laws of Nature the 

 second law deals with non-conservative processes. 

 According to a certain school of thought the laws 

 of dynamics and electro-dynamics, being conserva- 

 tive, might be left to run themselves, but the de- 

 generation of energy can only be taken to prove 

 that the world must have been started at some 

 time and must end at some future date — hence 

 the title. The author of this philosophical work 

 has evidently read widely in the literature of the 

 philosophy of science and in science itself. There 

 are discussions of 320 papers in it; indeed, almost 

 every pag-e is covered with references. He draws 

 the cautious conclusion that entropy does not 

 necessarily imply the existence of the Deity. 



.4 Text-hook of Qualitative Analysis of Inorganic 

 Substances. By Dr. S. A. Kay. Pp. vii-f8o. 

 (London: Gurney and Jackson; Edinburgh: 

 Oliver and Boyd, 192 1.) 75. 6d. net. 

 The practical details of analysis are described in 

 this book more minutely than is customary in 

 order to minimise the necessity of constant super- 

 vision of the student. All accounts of the theory, 

 even the chemical equations of the reactions, are 

 omitted. These are to be discussed orally. It 

 would, however, have been very much better to 

 have included them, since students usually carry 

 out the tests mechanically unless they have their 

 attention constantly directed to the chemistry in- 

 volved. The result is rather reminiscent of 

 cookery. 



Geography for Junior Classes. By E. Marsden 

 and T. A. Smith. Pp. viii-i-278. (London: 

 Macmillan and Co., Ltd., 1920.) 55. 

 The book under notice is suggestive of the bad 

 old geography furbished and brought up to date. 

 The last three parts cover the British Empire, and 

 a general view of the continents. The first is 

 mainly pure physics of a brand which is not 

 welcome. The phrase " Lines and Belts of 

 Equal Heat " is bad anywhere, but much worse 

 in a head-line. The book will not help to improve 

 school geography. 



