Oct. 31, 1889] 



NATURE 



641 



^' Chloral " to " Indigo," not only gives descriptions of all 

 important chemical elements and compounds contained 

 between these two heads, but contains short articles on 

 matters of general chemical interest, both of theory and of 

 practice. The editors desire to give their work a truly 

 international character, and we find valuable contributions, 

 not only from eminent English specialists, but from equally 

 competent authorities in Washington, Baltimore, and 

 Sydney ; whilst the presence of articles from the pen of a 

 lady — Miss Ida Freund, of Newnham— indicates that 

 scientific research and exposition are no longer to be 

 confined to the hands and heads of the so-called stronger 

 sex. 



In turning over the eight hundred pages of this closely 

 but clearly printed volume, one is first struck by the enor- 

 mous mass of detail with which the editorshave had to deal. 

 Not what to print, but what to leave out, is the problem 

 which all writers whose hard fate it is to have to record 

 the present condition of chemical science have to try to 

 solve. So enormous is the number of chemical sub- 

 stances which each day brings forth, so complicated are 

 the questions of theory which their existence raises — 

 questions which therefore vary from day to day and from 

 month to month — that to give a clear and yet complete 

 account of them may indeed be said to " pass the wit of 

 man." Still, this, Hke other difficult problems, has to be 

 attempted, and upon the way in which the attempt is made 

 depends the success or failure of a work of this kind. 

 Unless the student can gain a clear and correct idea of 

 the present condition of the science as regards the special 

 subject of the article upon which he seeks information, 

 the book is worse than useless. Unless the specialist can 

 find at least some sort of light and leading, and is supplied 

 with references for detail to the work done by his fore- 

 runners, the " Dictionary" will be of butpoorservice to him. 

 I venture, however, to think that, tried by both these 

 standards, the verdict of the public will be that the editors 

 have acquitted themselves well, and that this second 

 quarter of the new chemical " Dictionary " will rank as 

 high asthe first already does, and will bear favourable com- 

 parison with the older parent volume— now, alas, with its 

 author, numbered with those whose names have for us 

 only an historic interest. 



A dictionary merely confined to an enumeration of the 

 names, composition, properties, and constitution of the 

 many thousands of chemical compounds now known, 

 like the classical work of Beilstein — however valuable, 

 nay essential, to the student in the higher terms of the 

 series — is not what the beginner or the general scientific 

 reader or worker needs. He must have access to a 

 book in which both the general and the special prob- 

 lems of the science are discussed with full knowledge 

 of the position of the day. That this necessity has been 

 understood, and carefully provided for, is seen by the list of 

 articles furnished by special contributors, as well as by 

 glancing at those written by the editors themselves. In 

 that on " Chemical Classification," by Mr. Muir, we find 

 an able statement of the case, with the modest introduction 

 that " in the following article nothing more is attempted 

 than to sketch the outlines of the methods by the employ- 

 ment of which a fairly satisfactory scheme of chemical 

 classification may be attained," followed by the well-known 



definition of scientific classification given by Jevons in his 

 " Principles of Science." The article on " Crystallization," 

 by Mr. Harry Baker, is a model of perspicuity, and, whilst 

 much shorter than the article on the same subject in the 

 former edition, is sufficiently comprehensive for those who 

 wish to gain a knowledge of the principles of this 

 important branch. 



Of all the special articles, perhaps that by Prof. J. J. 

 Thomson, of Cambridge, on "Chemical Equilibrium," 

 and that on " Dissociation," by Prof. Threlfall, of Sydney, 

 are the most interesting and important. Both of these 

 articles seem to give a new tone to ordinary chemical life ; 

 they introduce the chemist to fresh fields and pastures 

 new. They point to the fact that the stream dividing 

 chemistry from physics has been bridged over, not only 

 at one point but at many, and that certain chemical 

 phenomena which beforetime have been considered as 

 apart and distinct can now be shown to be capable of 

 mathematical treatment, as belonging to the domain of 

 molecular physics. 



Whilst, however, in certain directions chemistry is 

 rapidly becoming a branch of physics, there are other 

 chemical phenomena which ally themselves with those 

 classed as biological, and of the most important of these 

 the " Dictionary " gives us an example in an excel- 

 lent though too short article on " Fermentation and 

 Putrefaction," by Dr. Rideal. Prof. Ira Remsen, of 

 Baltimore, contributes two articles, one on " Equivalency " 

 and one on " Formulae." In this latter he reminds us of 

 a fact known to but few that the symbolic notation intro- 

 duced by Dalton in 1808 had been preceded by an attempt, 

 though a less satisfactory one, in the same direction by 

 Hassengratz and Adel in 1787, though we may be sure 

 that of this attempt the Manchester philosopher was in 

 blissful ignorance. 



Other special articles, such as those on " Combustion 



and Flame," by Prof. Thorpe, on "Dextrin," by Mr. 



O'Sullivan, on " Cinchona Bark," by Mr. David Howard, 



amongst many others, have only to be mentioned to 



show the value and interest of the volume, which (in 



spite of necessary shortcomings, and of occasional 



unavoidable errors, which some may care to seek for, 



though I do not) appears to me to be well worthy of the 



name it bears, of the house which publishes it, and of the 



science which it expounds, and this is saying a great 



deal. 



H. E. RoscoE. 



OUR BOOK SHELF. 



Index of Spectra. By (W. Marshall Watts, D.Sc, &c. 

 Revised Edition. Manchester: Abel Heywood and 

 Son, 1889.) 



Dr. Watts is to be congratulated upon the completion 

 of his great undertaking— namely, to collect all the existing 

 measurements of laboratory spectra, and arrange them in 

 a manner convenient for reference. Since the last edition 

 of the book was published, seventeen years ago, spectro- 

 scopic research has made enormous progress, as a com- 

 parison with the new edition will show. This is no doubt 

 partly due to the increased number of workers, and 

 instrumental advances, and to a large extent to the 



