344 



NA TURE 



[February 7, 1901 



writer is acquainted. The subject is not an easy one, 

 and the reader must bring a certain concentration of 

 thought to its study ; but once he has mastered these 

 forty odd pages he will know the bearing of the critical 

 phenomena on physical chemistry with a thoroughness 

 that will leave little room for addition in his subsequent 

 reading, except on matters of detail. The work of Young, 

 Guye, Daniel Berthelot, Mathias, (Suldberg, Traube — all 

 receives consideration, and the impression left is one of 

 harmony and completeness, at least from the practical 

 empirical standpoint. 



Boiling-pjints, latent heats and specific heats are next 

 taken up, and the student will be surprised at many a 

 new way of looking at old familiar facts. Under the 

 heading of surface tension, the method of Eotvos and 

 Ramsay and Shields for determining molecular weights 

 is fully discussed, and a theoreticil connection shown 

 with Mathias's law of the rectilinear diameter. The sec- 

 tion on physical properties concludes with a chapter on 

 refractive indices and dielectric constants. 



The second portion of the book is entitled. Relations 

 between Chemical Properties and Composition. Its first 

 subdivision treats of the affinities of elements as displayed 

 in connection with their positive or negative character. 

 The author's views on this important general question 

 are summarised thus : Positive or negative character is 

 defined as the tendency to combine with positive or 

 negative electricity. The extreme positive and negative 

 elements, such as sodium and chlorine, show the strong- 

 est affinities, which suggests that their opposite electrical 

 charges play an active part in their chemical combina- 

 tion. Intermediate elements which are neither decidedly 

 positive nor negative, e.g. carbon, often show a tendency 

 to combine with themselves which is wanting in the 

 extreme elements. As second consequence of the 

 tendency to combine with electricity, we have the free 

 production of atoms charged with electricity — the ions — 

 in solvents like water which weaken the electrical at- 

 traction owing to their high dielectric constant. This 

 breaking up or loosening in its turn entails a facility for 

 reaction which is absent from intermediate elements, 

 carbon compounds, for example, being characterised by 

 great inertness in chemical action. Lastly, the pheno- 

 mena of affinity are most marked when the atomic weight 

 is small and the atomic volume large. 



A study of the affinities manifested by explosive com- 

 pounds and explosive mixtures is next entered on, and 

 then the influence of the separate elements on the 

 properties of compounds which they enter is taken up 

 in detail. The concluding sections are on the changes 

 in reaction velocity caused by certain elements and 

 groups, and the appearance of entirely new chemical 

 properties occasioned by the conjunction of certain 

 elements. 



On looking back through the book as a whole, one 

 notes the circumstance that Parts i. and iii, are better 

 done than Part ii , and that, on the whole, the physical 

 portions are perhaps at a higher level of excellence than 

 the chemical portions. It is everywhere evident, how- 

 ever, that the material has been wrought into form by a 

 powerful thinker, who sees deeper and more clearly into 

 his subject than any of his contemporaries. 

 A comparison of the English and French translations 

 NO. 1632. VOL 03] 



shows that the former, being more literal, is more difficult 

 to follow than the latter. The freedom of translation in 

 the French version is, however, not attained at the ex- 

 pense of accuracy ; indeeJ, in more than one passage the 

 sense of the original is better given in the French trans- 

 lation than in the English. To translate dann by "there- 

 fore" or even by "then," when it is merely used for the 

 purpose of enumerating points of the argument (as in 

 p. 89 of the original, and p. 98 of the English version), 

 gives a false impression of logical sequence ; and to 

 ira.r\-s\a.\.tAffinifdtsdussertingen by " indications of affinity" 

 (same page) is scarcely exact. 



To the French version are appended two notes by the 

 translator— one on Dieterici's modification of van der 

 Waals's equation, the other on Kanonnikoff's " real 

 density," derived from the formula of Lorentz and 

 Lorenz. 



Whilst strongly recommending the English version to 

 all interested in physical chemistry, the writer would 

 express the hope that in a future edition the three parts 

 will be paged and bound as one volume, that the price 

 will be reduced to a figure more suited to the size of the 

 work and the means of the majority of students, and, 

 finally, that the book will be provided with an index, the 

 want of which in the present edition materially detracts 

 from its usefulness. J. W. 



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