REVIEWS 315 



a mathematical or scientific training, are desirous of obtaining an insight into 

 the principles upon which the theory is based, and of understanding its bear- 

 ings in the realms of science and philosophy. The book has been written for 

 the average reader, and the author has spared no pains to put the ideas into 

 a simple form, many homely illustrations being used to make the point of an 

 argument clear. 



About one-half of the book is occupied with the special theory, and the 

 modifications which it necessitated in our ideas of space and time. Then 

 follows an account of the general theory, involving as a consequence the solu- 

 tion of the problem of gravitation. A brief account is also given of the bearing 

 of the theory on the general question of the structure of space. 



Prof. Einstein is careful to point out in his preface that the "work presumes 

 ... a fair amount of patience and force of will on the part of the reader." 

 The average reader must be prepared to find some of the conceptions difficult 

 to grasp at first, and will be advised to reread the book in order thoroughly 

 to understand it. There is certainly no other work available covering the 

 same extent of ground in such an elementary manner. Dr. Lawson is to be 

 congratulated on the service he has rendered by making Prof. Einstein's 

 account available in English in this excellent translation. 



H. S. J. 



CHEMISTRY 



Cours de Chimie. Par R. de Forcrand, Professeur de la Faculte des 

 Sciences ; Directeur de I'lnstitut de Chimie de I'Universite de Mont- 

 pelier, [Vol. i, pp. viii + 437 ; vol. ii, pp. 527.] (Paris : Gauthiers- 

 Villars & Cie, 1918-19.) 

 In its scope and general arrangement, this textbook of chemistry for stu- 

 dents difiers considerably from the more usual type of textbook with which 

 we are familiar on this side of the Channel. 



Vol. i is divided into two main sections, " Generalites " and " Chimie 

 Min^rale," whilst vol. ii deals with " Chimie Organique," " Chimie Analy- 

 tique," and " Applications Num^riques," so that a student who has been 

 through the entire course will have a very considerable knowledge of the 

 fundamental principles of the subject. It is, of course, somewhat unusual 

 to include both the theoretical and practical sides of Chemistry within the 

 limits of the same book, but it has the advantage of compactness. 



The arrangement also of the section on Organic Chemistry does not 

 follow the usual plan of dividing the subject into the aliphatic and the aro- 

 matic divisions and so on, but the whole section is split up into some nine- 

 teen chapters divided according to the " Fonctions " dealt with ; thus the 

 " Septieme fonction, C^tones," deals with acetone, camphor, sugars, anthra- 

 quinone, cellulose, and alizarin, a fairly mixed batch ! 



This method has, of course, certain obvious advantages, but probably 

 English readers will prefer the more usual arrangement of dividing into 

 aliphatic and aromatic groups, and then further subdividing according to 

 the number of carbon atoms. 



The textbook sufiers from the usual failing of French works in having 

 no index other than the " Table des Matieres " at the end, but is worth ex- 

 amination as a variant from the usual run of books on chemistry. 



F. A. M. 



Histoire de la Chimie. Par Maurice Delacre, Membre de I'Acaddmie 

 Royale de Belgique, Professeur a I'Universite de Gand. Ouvrage 

 couronne par I'lnstitut de France. (Prix Binoux.) [Pp. xvi -{- 632.] 

 (Paris : Gauthier-Villars & Cie, 1920.) 



We have not a few histories of chemistry from Thomson's History to Kopp's 

 Geschichte and onwards, but Prof. Delacre has written a book which pos- 



