May 6, 1904.] 



SCIENCE. 



731 



ary phenomena between two difEerent kinds of 

 matter. It will be seen at once that the order 

 of presentation adopted by Kundt is one which 

 lends itself most easily to simplicity of treat- 

 ment, and is not at all concerned with the log- 

 ical development of the subjects. Throughout 

 the whole book all mathematical points are 

 avoided and the utmost required is a most 

 elementary knowledge of geometry. There is 

 no discussion whatever as to our mode of un- 

 derstanding what is meant by mass or force, 

 and no attempt is made to show the logical 

 connection between various subjects. As one 

 reads the lectures one is struck with their 

 clearness of thought, the beauty and vigor of 

 expression, but above all with the fact that 

 from the standpoint of interest to the class it 

 would be impossible to present the subject in 

 a better manner. All difficulties seem to 

 vanish and the student is led from one phe- 

 nomenon to another, and back again to more 

 complex illustrations of the former, until all 

 the essential facts of the subject are brought 

 before him. If the treatment of the subjects 

 of electricity and magnetism is analyzed, it 

 is seen to be of the same general character as 

 that of mechanics. There are a few chapters 

 on the subject of electrostatic phenomena fol- 

 lowed by a discussion of magnetism; then the 

 ideas of electrostatic potential and capacity 

 are introduced, and this leads to a discussion 

 of electric currents. Special emphasis is laid 

 throughout the whole book upon the descrip- 

 tion of instruments for measurement and for 

 ordinary laboratory use, and the question of 

 the development of ideas is in many cases sub- 

 ordinated to this. A marked illustration is 

 afforded by the fact that, since an induction 

 coil is ordinarily used in producing electric 

 currents through gases, therefore the whole 

 subject of induced currents is taken up before 

 the chapter on conduction through gases. An 

 illustration of the fact that the main object 

 of these lectures is to describe physical phe- 

 nomena and not explain them is shown by 

 noting that there is no discussion whatever as 

 to the energy of electrostatic or electromagnetic 

 fields or of the reasons underlying electric and 

 magnetic attraction and repulsion, and yet 

 interference with convergent polarized light, 



quartz compensators, systems of multiplex 

 telegraphy, etc., are discussed in full. 



The publishers of this volume in their pre- 

 liminary announcement express the belief -that 

 it will be useful to those who are following 

 courses in physics as a text-book to accom- 

 pany their lectures, and also to the scholar in 

 general as an introduction to physical phe- 

 nomena. They say, moreover, that every one 

 who is familiar with the teaching of physics 

 will receive, as he reads the book, continual 

 pleasure from the elegant and original method 

 of presentation of facts already known to 

 him. These statements of the publishers fall 

 short of the whole truth. There is no book at 

 the present time, so far as known to the re- 

 viewer, which presents the subject of physics 

 in such an attractive manner, and a trans- 

 lation of it in English would be of the greatest 

 use in many colleges and schools. To the 

 teacher of physics the great interest of the 

 book lies in the fact that one has here an 

 opportunity of seeing how a great master in the 

 art of lecturing prepared his course ; and, fur- 

 ther, because he can not fail to learn many 

 ways by which the subject may be made more 

 interesting to his class and at the same time 

 less difficult. J. S. Ames. 



The Johns Hopkins Univeesity. 



Disinfection and the Preservation of Food. 

 By Samuel Rideal, D.Sc. New York, John 

 Wiley and Sons. 8 vols., 504 pages, illus- 

 trated. $4.00. 



This valuable work gives in convenient 

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 fection and the preservation of food. The 

 greater part of the work is devoted to the sub- 

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 poses, but also in a small way in private 

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 disinfection are described and their methods of 

 application explained. 



The different methods are grouped under the 

 heads ' Mechanical Disinfection,' ' Steriliza- 

 tion by Heat ' and ' Chemical Disinfectants.' 

 Both sterilization by heat and the use of 

 chemical disinfectants are also employed in the 



