APPENDIX. 



NOTICES OF BOOKS. 



The Elements of Pliysics. By Edward L. Nichols and William S. 

 Franklin. Vol. iii. Light and Sound. The Macmillan Co., 1897. 



This is the third and concluding volume of a text-book, the second 

 volume of which was noticed in Science Progress (April, 1897). In 

 this volume the two branches, Light and Sound, are considered together 

 under the general head of wave motions which affect the sensory nerves. 

 The remarks made with reference to the second volume apply in the 

 case of the third volume, with the exception that in this volume the 

 references have been put in. 



Studies in CJiemical Dynamics. By J. H. Van't Hoff. Revised and 

 enlarged by Dr. Ernst Cohen. Translated by Dr. Thomas 

 - Ewan. Amsterdam : F. Muller & Co. London : Williams & 

 Norgate, i8g6. 



The first edition of Professor Van't Hoff's Etudes de Dynamique 

 Cliimiqne being exhausted, the question of issuing a new edition was 

 suggested, but the difficulty arose that the Etudes represented the stage 

 of the author's chemical thinking at the time of their publication about 

 twelve years ago, but that now-a-days most thinkers have passed beyond 

 this stage. To make many changes in the new edition would, however^ 

 have taken away from the work its desired documentary character, 

 while to change nothing would have contributed nothing towards 

 making the contents acceptable to the public. Under these circum- 

 stances Dr. Cohen undertook to revise the Etudes, so as to include not 

 only the old matter, but also an account of the researches which have 

 been engendered by it, so as to form a record of the work carried out in 

 Van't Hoff's laboratory. 



The book is divided into four sections dealing with (i) the course 

 of chemical change, (2) the influence of temperature on chemical change, 

 (3) chemical equilibrium, and (4) affinity. 



In each case, in addition to a complete account of the experiments 

 which have been made, and the apparatus used, there is a theoretical 

 discussion, the experimental facts being used to test the accuracy of the 

 theory. It must not be supposed that the experiments made in Van't 

 Hoff's laboratory are exclusively referred to, references are given to work 

 bearing on the subject done elsewhere, and the results obtained are quoted. 



The translation is all that could be desired, and the book will be 

 of great use to English-speaking chemists and physicists both as show- 

 ing in a clear and striking manner what has been done in the subject, 

 and as a source from which many instructive and probably fruitful 

 suggestions may be obtained. 



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