58o 



NA TURE 



[April i8, 1895 



and vaccinia are two perfectly distinct diseases, calls for 

 some comment in the light of recent investigations, and 

 the omission of any reference to the statistics of the 

 Sheffield epidemic of 18S7-8 is a serious blot on any 

 work dealing with the history of small-pox. The im- 

 munity from small-pox which infants and children enjoy 

 at the present day, receives the not very satisfying ex- 

 planation that they now have measles, whooping-cough, 

 scarlatina, and diphtheria instead ! 



In the later chapters the author deals with the last- 

 mentioned diseases and with infantile diarrhoea, 

 dysentery and cholera, the history of which is traced 

 with great care and accuracy. It would indeed be 

 difficult to praise too highly the pains which the author 

 has taken in the collection and arrangement of his 

 historical facts. But he has chosen to add, in many 

 places, considerations as to the nature and causes of the 

 diseases he chronicles, which frequently do not cover all 

 that is known about the subject, and would have been 

 better omitted or treated separately from the historical 

 portions of the book. It is true that, in some cases, there 

 are strong reasons for believing that the virus of a disease 

 may reside in the soil, but it is by no means true for 

 others. It is true that we are ignorant of the precise 

 nature of the virus of many of the diseases discussed in 

 the book ; but it is not the case with all. Yet in no 

 single passage dealing with atiology do we find any 

 reference to even well-established bacteriological facts. 

 It may be that much studying of the records of the past 

 begets a tendency to a medieval frame of mind. Cer- 

 tainly Dr. Creighton's views on telluric influences will 

 ■ not commend themselves to the modern pathologist, 

 though, like the subjects he treats of, they may possess 

 a historical interest. 



But it is a great merit of the book that it can be 

 read with pleasure and instruction by all, however the 

 reader may differ from the author in pathological creed ; 

 and Dr. Creighton may be congratulated upon the com- 

 pletion of so excellent and thorough a history of epidemic 

 diseases in this country. 



OUR BOOK SHELF. 



Crundziige der mathemalischen Cheniie. Von Dr. G. 

 Helm. (Leipzig : Wilhelm Engelmann, 1894). 



The treatment of the subject-matter of this book is based 

 on the view that in its present state of development, that 

 branch of physical chemistry which relates to chemical 

 change can be di?cussed from a general standpoint, in- 

 asmuch as it affords the clearest and most complete 

 confirmation of the principle of the conservation of 

 energy. 



The applications of this principle to chemical inter- 

 actions arc first illustr.ited by means of the different kinds 

 of thermal measurements, numerical examples being 

 given, the solutions of which, here as elsewhere in the 

 book, are particularly neat. Mechanical forms of energy 

 attending chemical change, in particular the volume 

 energy of gases, are also discussed. The author next 

 points out that the measures of the different forms of 

 energy are composed of two factors, one of which is all- 

 important in determining the direction of the energy 

 change. Temperature and entropy are shown to be tlie 

 factors of heat energy, and a clear and concise account 

 of the thermodynamics of perfect gases is given, in order 



NO. 1329, VOL. 51] 



to arrive at the shape of the entropy function, which is 

 of course known in this particular case. The relations 

 between heat energy and volume energy, and between 

 heat energy and electrical energy, are then set out at 

 length. 



The author here indicates how terms involving what 

 he calls the "chemical intensity" of the reacting sub- 

 stances enter into the energy equations. Chemical 

 intensity is what Gibbs originally termed the " potential " 

 of the substances, and this function, it is hoped, will 

 eventually be shown to be the mathematical expression 

 of chemical affinity. 



The third section of the book is devoted to the pro- 

 perties of chemical intensity. The general method of 

 deriving the law of mass action is given, and chemical 

 equilibrium, the properties of dilute solutions, and the 

 velocity of chemical reactions are brought under the 

 sway of the energy equations. The last section contains 

 the treatment of the phenomena which may be grouped 

 around Gibbs's phase rule, and of reactions depending 

 on several parameters. 



The book is the only one which is exclusively devoted 

 to chemical energetics, and to the student possessed of 

 sufficient mathematical knowledge it offers an admirable 

 account of the present state of the subject. J. W. R. 



Die Bearbeiiung des G/ases auf dem Blasetischi: Von 

 D. Djakonow und W. Lermantoff. Pp.154. (Berlin: 

 R. Friedliinder and Sohn, 1895.) 



The original edition of this book was in Russian, and 

 the authors, one of whom, D. Djakonow, is now dead, 

 were demonstrators in chemistry at St. Petersburg Uni- 

 versity. The instruments and methods employed by 

 glass-blowers are set forth in detail, together with de- 

 scriptions of the kinds of glass best suited for different 

 work. A very full and practical account is given of the 

 construction, graduation, and calibration of thermo- 

 meters ; but to carry out these operations thoroughly, 

 some experience is required. Work more suitable for 

 the 'prentice hand fills the greater part of the book. 

 Every operation in glass-blowing and manipulation likely 

 to be needed in physical and chemical laboratories, 

 appears to be described ; while the diagrams illustrating 

 the stages in the construction of the different pieces of 

 apparatus, will greatly assist in training students to 

 become skilled workers. 



Problems and Solutions in Elementary Electricity and 

 Magnetism. By W. Slingo and A. Brooker. Pp. 108. 

 (London : Longmans, Green, and Co.) 



Model answers to examination questions may prove a 

 blessing or a curse, according to the way in which 

 teachers use them. Herein are answers to questions in 

 electricity and magnetism (elementary stage), set at the 

 Science and Art Department's examination from 18H5 to 

 1S94, together with a series of original questions. The 

 teacher who wishes to train his class to answer ques- 

 tions clearly and concisely, will find suitable exercises 

 in composition in this book, and he will also find the 

 volume an inducement to cram his students with 

 undigested information. 



Qualitative Chemical Analysis of Inorganic Substances. 

 " (New York : American Book Company, 1895.) 



This work consists of a series of analytical tables, sup- 

 plemented by explanatory and descriptive notes, and 

 working directions. It makes no pretence to originality, 

 and is hardly a book wc should like to see widely adopted 

 by students of elementary practical chemistry. The tables, 

 which were prepared (or use in Geort;ctown College, 

 Washington, D.C., present few points o( interest or 

 value to teachers ol chemistry in our schools. 



