230 



SCIENCE 



[N. S. Vol. XXIX. No. 736 



traces of Co and Ni, is heated to drive off H^S, 

 and cooled; it is then treated with an excess 

 of KOH, oxidized with Br water or H,0,, and 

 filtered. The residue may contain re(0H)3, 

 Mn03H^ and traces of CrCOH),, Co(OH)3, 

 M(0H)3. The filtrate may contain K,CrO„ 

 AIO3K3 and ZnOJi,. The Cr is tested for 

 by oxidizing an acidulated portion of the 

 filtrate to perchromic acid by H^O,. Another 

 portion of the filtrate is exactly acidulated 

 with HCl, and precipitated by sodium acetate 

 as aluminium basic acetate, thus securing the 

 detection of very small amounts of Al. The 

 filtrate from the oxyacetate contains the Zn 

 which is precipitated as sulphide by H,S. 

 Iron and manganese are tested for by dis- 

 solving one portion of the residue in HCl, and 

 adding KCNS, or Fe(CN)„K„ and by fusing 

 another portion of the residue with ISTa.COj + 

 KNOj. The presence of traces of compounds 

 of Cr, Co, Ni, not interfering with these tests. 

 This method will be found simpler, shorter, 

 and fully as accurate as the barium carbon- 

 ate method, which is so generally recom- 

 mended, when Cr, Mn and Fe are all present 

 in the substance analyzed. 



In the chapter on solutions the treatment of 

 sulphides and chlorides insoluble in acids is 

 noticeable. 



In the chapter on preliminary treatment the 

 introduction of the Hempel reduction meth- 

 ods is praiseworthy. 



The phase-rule is entirely omitted; just 

 why it is hard to see. One may say that be- 

 ginners can not understand it, but this is not 

 a book for beginners. However, as Dr. Bott- 

 ger is chief assistant in the Leipsic laboratory, 

 he must be credited with due consideration of 

 the theories to be introduced or omitted. 



Elementary physical chemistry throws such 

 a flood of light on the problems of analysis 

 that the opponents of its use for this purpose 

 are fewer every year; although among the new 

 manuals are some which practically differ 

 from the older books only in adding the word 

 " ion " to the name of the element, and freely 

 using + and — signs ; such books do not il- 

 luminate and make no converts. 



The present book, it is true, is too large and 

 too detailed for American college students, 



but any one who intends to write a laboratory 

 manual — and who does not write one? — ^will 

 do well to read Dr. Bottger's book carefully. 



It would be well if the author should ar- 

 range with his American translator to pub- 

 lish an abbreviation of this book for college 

 use, containing the theoretical part and ex- 

 periments without change, but cutting down 

 the remainder to a third of its present size. 

 This is practicable, as much of the present 

 material should be omitted for college use, 

 and as Dr. Bottger's German is extremely 

 diffuse. Such a book would be very valuable 

 for college students in their second laboratory- 

 year. 



The book, as it is, should be studied by 

 graduate students, and especially by teachers, 

 who will find in its pages simple explanations 

 of more than one puzzling phenomenon. It 

 is to be hoped that the book will meet with 

 the recognition which it merits. 



E. Renouf 



A Treatise on Chemistry. By H. E. RoscoE 

 and C. ScHORLEMMER. Volume II. : The 

 Metals. New Edition, completely revised 

 by H. E. RoscoE and A. Harden. Pp. 

 xii-(-1436. New York, The Macmillan 

 Company. 



Sir Henry Roseoe is to be congratulated 

 most heartily on the revision of the well- 

 known " Treatise on Chemistry." It is sel- 

 dom that an author lives to see such an ex- 

 tensive work useful through thirty years and 

 at the end of that time appear entirely fresh 

 with all of the most recent developments in 

 theory and application. The book bears the 

 strong personal impress of the author and is 

 delightful reading on account of the intimate 

 historical presentation of the various subjects. 

 The scientific, practical and historical are so 

 nicely interwoven as to make the book most 

 readable and valuable. 



The introduction of material on Werner's 

 valence theoi'y, the phase rule, radio-activity, 

 Thomson's corpuscular theory and other recent 

 developments has added much to the value of 

 the book. In addition to these an account 

 of recent work on alloys has been added, al- 

 though the treatment is not entirely satisfac- 



