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Part II. Modern discoveries and theory (covering radium, electrons, solu- 

 tions, catalysis, colloids, etc.). 

 „ III. Modern applications of chemistry (including such diverse matters 

 as water, metals, coal-tar dyes and drugs, explosives, and the 

 fixation of atmospheric nitrogen). 

 „ IV. Modern progress in organic chemistry (including sugar, albumens, 

 enzymes, etc.). 

 It will be seen, therefore, that the work is most comprehensive ; but, despite 

 the large amount of material dealt with, it is always concise and eminently 

 readable. The illustrations are admirable and the book well got up ; in fact, one 

 can imagine no better present to a boy (of any age from eight to eighty) than a 

 copy of this work. 



One may venture to congratulate both Sir William Tilden and the publishers 

 on the production of so excellent a volume. Frederick A. Mason. 



Ozone, Its Manufacture, Properties and Uses. By A. Vosmaer, Ph.D. [Pp. 

 xii + 197.] (London : Constable & Co., 1916. Price 10s. bd. net.) 



OZONE, like many other electrically formed substances, has always preserved for 

 the general public an atmosphere of mystery, and its production has been 

 regarded by the scientific " man in the street " as one of those subtle phenomena 

 that are not susceptible of accurate experimental verification. In his preface 

 Dr. Vosmaer states that there are many publications on ozone that cannot be 

 classed otherwise than as commercial information and advertising matter. He 

 states, however, that the main object of this book is to " give a full outline of our 

 personal experience," but he adds : " That same experience has made us very 

 critical about outside information." The account given of the properties and 

 chemical structure of ozone is incomplete and unsatisfying, and this applies to a 

 good many other sections of the book. 



The chapter, however, dealing with the brush discharge and the conditions 

 which underlie its successful production is excellent ; it contains a good summary 

 of our knowledge of the subject and will be useful for reference, but the book 

 lapses again when the author begins the description of the various apparatus that 

 have been constructed for the production of ozone, or " ozonators." The Schneller 

 system is dismissed as follows : " When once somebody has proven a generally 

 accepted statement, in this case the necessity of a solid dielectric, to be wrong, 

 it is easier for some one else to continue research in that line of deviation (!). 

 That credit should be given to Schneller." Dr. Vosmaer, however, is equally 

 frank about his own system in which no dielectric was used. It "has had to undergo 

 the same fate as all the other attempts to go round the dielectric. Neither this 

 nor the Otto nor the Schneller nor the Tesla system has succeeded." 



The descriptions of successful ozonators are not very clear or detailed, and 

 no information is given which could be of use to those desiring to construct such 

 apparatus for experimental purposes. The author, however, gives an alluring 

 account of the uses of ozone. One is apt to feel that the scientific attitude 

 of complete detachment from financial results is prejudiced when one comes 

 across such statements as these : 



" There is any amount of evidence to be had that, in Europe, the success is 

 irrefutable, and yet here in America people are not daring enough to even try. 



"The explanation is not far to seek : the application of ozone is of a very simple 

 nature for those that know how to handle it, but it is no easy matter for those that 

 have looked at it, and believe themselves clever enough to copy it." 



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