332 



SCIENCE 



[N. S. Vol. XXXIII. No. 844 



A new edition of " Erdmann " will be wel- 

 come to every chemist who has read the earlier 

 editions. This book is well known but not as 

 well as it deserves. When the first edition ap- 

 peared thirteen years ago, it was recognized as 

 the best existing one-volume text-book of de- 

 scriptive chemistry; each succeeding edition 

 is an improvement on its predecessor. 



The present fifth edition has a melancholy 

 interest as the last work of the author. Erd- 

 mann wrote the preface but a few days before 

 his accidental death by drowning while sailing 

 on a lake near Berlin. He was an active 

 worker in several fields of chemistry, but will 

 be best remembered for the " Lehrbuch." 



What are the chief features of this book? 

 It is written for advanced students, not for 

 beginners. It is essentially descriptive. It 

 opens with a condensed but admirably clear 

 and complete statement of physical-chemical 

 laws and methods contained in an introduc- 

 tion of 84 pages. The remainder of the book 

 treats of the elements and their compounds, 

 and is chiefly descriptive, both chemical and 

 physical properties being considered; tech- 

 nical methods and experiments profusely illus- 

 trated by excellent diagrams form a prominent 

 feature of the book. 



To give the reader an idea of the scope of 

 the book, the headings of the paragraphs of 

 one of the shorter and simpler chapters may 

 be given. It is worth the reader's attention. 

 The chapter on hydrogen fills 21 pages; it in- 

 cludes 4 tables, 22 diagrams and a beautiful 

 colored plate of the spectra of hydrogen, oxy- 

 gen and nitrogen. The chapter begins with 

 the present and the old names of the element 

 in German and the present name in English, 

 French, Eussian and Spanish. The physical 

 constants follow; then the following para- 

 graphs — occurrence in the universe; on the 

 earth free and combined; relative weights of 

 chief elements in earth's crust compared with 

 relative number of their atoms; discovery; 

 preparation; hydrogen as by-product; as unit 

 of gas densities; free hydrogen has the den- 

 sity 2; specific gravity of hydrogen compared 

 with air and with water — determinations of 

 Eegnault, Eayleigh, Cooke, Leduc, Morley 



and Thomsen; normal pressure and normal 

 temperature; polarization; molecular speed; 

 difl^usion; effect of change in temperature and 

 pressure on expansion; hydrogen the legal 

 basis of thermometry; Kelvin's phenomenon; 

 liquid hydrogen; critical pressure; chemical 

 activity; action on water, on the halogens; on 

 oxygen; combustible; metallic modification of 

 hydrogen; nascent state; as unit of atomic 

 weights; density in palladium alloy compared 

 with densities of alkali-metals; as reducing 

 agent; practical uses; lifting capacity of bal- 

 loons; filling balloons; hydrogen as fuel; 

 spectrum. Then follows the section on ex- 

 periments and technique with the diagrams. 

 In addition to the familiar apparatus and ex- 

 periments may be mentioned Bucher's appa- 

 ratus for quick generation of large volumes of 

 hydrogen from aluminium and sodium hydrox- 

 ide, or from calcium hydride (hydrone) ; 

 Kammerlingh-Onnes's apparatus for liquefy- 

 ing hydrogen; the triple-walled Weinhold 

 modification of the Dewar flask; experiments 

 with liquid and with solid hydrogen; griess- 

 heim process for preparation of large quanti- 

 ties of hydrogen. 



Not only do we find matter in this book 

 which is not given in other one-volume text- 

 books, but we find something new concerning 

 nearly every element and important com- 

 pound which was not in the last edition, for 

 the author introduced a reference to every 

 important discovery if it appeared in the 

 journals before the edition went to press. 



The elements are treated in the main in the 

 order of the periodic system, though Erdmann 

 makes but little use of the system, describing 

 it in the closing chapter. His own arrange- 

 ment of the elements in a spiral curve — given 

 on a separate table — is interesting. 



A singular flaw in the book is the lack of a 

 proper treatment of the subject of steel. The 

 data given are scant, scattered and empirical. 

 Thus vanadium steel is barely mentioned and 

 only in the chapter on vanadium. This is, 

 however, but a small matter compared with the 

 general excellence of the book. Translations 

 are not known to the reviewer. The frequent 

 appearance of new editions has probably de- 



