February 14, 1901] 



NA TURE 



369 



It is interesting to note how this very earnest and 

 conscientious teacher treats his subject, as he evidently 

 endeavours to present the main results of scientific 

 research to his readers so that they may be prepared for 

 the shock of a possible future meeting with scientific 

 doctrines which might imperil their faith. 



The "Church" has, very wisely, not pronounced 

 definitely on many scientific problems, and concerning 

 these it is open to an intelligent Roman Catholic to hold 

 fairly advanced views ; for example, the cosmogony of 

 the Bible is one of these, and the reader is permitted to 

 take his choice of the three main interpretations of this 

 account. The most, too, is made of our ignorance con- 

 cerning the origin of life and the actual precursors of 

 man. The author regards himself as an evolutionist, but 

 he is not a thoroughgoing one, as he distinctly affirms 

 that the theory of evolution can neither be applied to the 

 origin of life nor to man. He asserts that 



" evolution, even had it realised the progression which 

 unites all animals in one nature, could not have produced 

 that new creation which is known as an intelligent and 

 free man.'' 



The author admits that .the volume has no scientific 

 pretensions, and he goes on to say " were it judged with 

 the utmost rigour it would not disturb me." All the 

 same, the book would have been less open to criticism if 

 it had been looked over by specialists, as there are many 

 statements of theories or facts that, to say the least, it 

 would have been much better to have put differently, and 

 there are many errors of nomenclature and misprints 

 that should have been avoided. For example, Noctiluca 

 is called a "jellyfish" (p. 75), Aurelia oecrita {sic) is 

 termed a Madusa (p. 82). As examples of errors of 

 fact may be instanced, the Australians are credited with 

 a " wide head "(p. 368) ; the Bushmen are degenerate 

 Hottentots, and these, according to "eminent ethno- 

 logists," are "emigrant Egyptians, debased and deforrned 

 by misery" (p. 372). 



We have given this book as much space as it 

 deserves as a popular exposition of human origins ; but 

 nevertheless it is probable that it will be of service, as it 

 should make some religious people think on subjects that 

 they too often ignore, and, at all events, it will indicate 

 to " good Catholics " that certain of their own religious 

 teachers do not entirely repudiate modern science or 

 entirely reject the theory of evolution. 



OUR BOOK SHELF. 



Atti delta Fondazione scientifica Cui{nola. Vol. xvii. 

 Pp. xxvi -f- 355. (Milan : Tip Bernardoni di C. 

 Rebeschini, ec, 1900.) 



Under the Cagnola foundation, two prizes are annually 

 awarded for essays on subjects proposed by the founder, 

 and one prize of about 100/., with a gold medal of the 

 value of 20/., are awarded on a subject chosen by the 

 Reale Istituto Lombardo. The theme for 1898 was a 

 •critical exposition of the theory of electrical dissociation, 

 and the successful memoir by Profs. Angelo Battelli and 

 Annibale Stefanini forms the subject of the present 

 volume. 



Among the various theories of solution, that of van 't 

 Hoff, which regards the dissolved substance in a dilute 

 solution as existing in the gaseous state, has found much 



NO. 1633, VOL. 63J 



favour ; but determinations of molecular weight derived 

 by this hypothesis do not agree, especially in the case 

 of electrolytes, with those obtained by other methods or 

 deduced from the chemical formulae. This circumstance, 

 coupled with the fact that the least electromotive force 

 suffices to generate a current in an electrolyte, had already 

 led Clausius to replace the hypothesis of Grotthus by 

 other theories ; and Arrhenius, observing that the 

 anomalies in the osmotic pressure and the freezing-points 

 occur exclusively in solutions of electrolytes, was led to 

 the hypothesis that these contain the acids and salts in 

 a state of dissociation, increasing with the dilution. 



This hypothesis of electrolytic dissociation has been 

 put by the authors to a variety of tests in connection with 

 the mechanical phenomena of osmotic pressure, optic 

 phenomena, thermal phenomena connected with freezing- 

 and boiling-point determinations, and, lastly, electric 

 phenomena ; and while many of the results favour the 

 hypothesis of the existence of free ions in solutions, 

 others are difficult to reconcile with this theory. Thus 

 the degree of dissociation required to account for optic 

 phenomena does not always agree with that deduced from 

 cryoscopic or ebullioscopic observations, or from electric 

 conductivity. Moreover, the authors do not consider it 

 conclusively proved that there is no inferior limit to the 

 electromotive force sufficient to set up a current in an 

 electrolyte. 



It will be thus seen that Profs. Battelli and Stefanini 

 have opened up a wide field of discussion in connection 

 with electrolytic theories, and that their work, both 

 theoretical and experimental, will be of no small assist- 

 ance to chemists and physicists interested in researches 

 in this subject. 



An Elementary Treatise on Qualitative Chemical 

 Analysis. By Prof. T. F. Sellers, A.M. Pp. 160. 

 (Boston : Ginn and Co., 1900.) 



The author justifies his contribution to the long list of 

 analytical works by pointing to the inevitable gap. The 

 gap no doubt exists. The question is whether it is desir- 

 able to fill it. We have analytical books which mean 

 business, and, being written for analysts and not for 

 students, are crowded with practical details. Then there 

 are the countless examination cram books, which by 

 tabular and other devices direct the student by the 

 shortest cuts to his ultimate goal— the discovery of the 

 constituents of salts, simple and complex. The present 

 little volume is to fill the gap which lies between these 

 two extremes, and its advantages are set forth in the 

 preface under six principal heads and eight subsidiary 

 ones. Without transcribing literally these manifold 

 recommendations, it may suffice to say that the book 

 opens with the principles of analytical chemistry by 

 introducing the theory of solution, osmotic pressure and 

 electrolytic dissociation, and proceeds with the usual 

 series of qualitative tests for bases and acids and their 

 methods of separation. 



However desirable it may be for even an elementary 

 student to gain some knowledge of analytical chemistry 

 based upon the modern theory of solution, a beginner 

 should first be confronted with his experimental facts. 

 A reversal of the present order might therefore be 

 adopted with advantage. An advantage, too, would be 

 derived from the mtroduction of a few illustrations, 

 descriptive of the apparatus mentioned in the text. 



As to whether a student, such as the author contem- 

 plates, who does not intend to specialise in chemistry, 

 gains very much from the detailed study of analytical 

 operations, is open to question. 



The study of qualitative analysis as a substantial part 

 of elementary practical chemistry has been determined 

 largely by tradition, partly, too, by the exigencies of 

 examination, to which it readily lends itself; but it is 

 worth consideration whether the emphasis laid upon it 



