90 



SCIENCE 



[N. S. Vol. XXVIII. No. 707 



Dublin. Together with an introduction to 



the Study of Physical Chemistry, by Sir 



William Eamsay, KC.B., F.E.S. Pp. 



Ixi + 381. London, Longmans, Green and 



Co. 1908. 



The term stoiohiometry which originally 

 was applied to the calculation of chemical 

 equivalents has been extended by Ostwald to 

 include not only the determination of atomic 

 and raolecular weights, but the study of the 

 properties of solids, liquids, gases and solu- 

 tions as well. It is in this broader sense that 

 the author uses the word in the title of the 

 present volume, which may be regarded as 

 the most satisfactory of this admirable series 

 of texts which we owe to Professor Eamsay. 



Unfortunately many of the text-books which 

 appear nowadays are characterized by a sort 

 of inbreeding, each one reading like a reas- 

 sortment of the sterotyped pages of its prede- 

 cessors. This fault the author has avoided 

 to a remarkable degree. The interest of the 

 reader is held not only by the refreshing 

 novelty of the treatment but also by the in- 

 troduction of much comparatively unfamiliar 

 material and many new tables and figures. 

 If a criticism were to be made it would be 

 that the author's zeal in the exposition of ex- 

 perimental results has caused him to neglect 

 those fundamental thermodynamic considera- 

 tions which would have added much to the 

 sy mm etry and logical completeness of his 

 work. 



Never has a simple experiment, carried out 

 with the highest accuracy and scientific 

 honesty, been rewarded by more signal con- 

 sequences than Lord Ealeigh's determination 

 of the density of nitrogen. The continued 

 study of the small discrepancies which he 

 found, and which might have been glossed 

 over by a less critical observer, have led 

 directly on the one hand to the discovery of 

 the five new elements of the argon family, and 

 on the other to the complete revision of our 

 accepted table of atomic weights. The work 

 of D. Berthelot, Guye and others has estab- 

 lished the complete validity, at very small gas 

 pressures, of the principle of Avogadro, and 

 has enabled them by physico-chemical means 



alone to determine the atomic weights of a 

 considerable number of elements with an ac- 

 curacy which rivals that attained in the most 

 refined chemical analyses. How this method 

 has led to a notable amendment of Stas's 

 value for the atomic weight of nitrogen, and 

 thence indirectly to a modification of many 

 other important atomic weights, is fully de- 

 scribed by the author. He discusses also some 

 of the more important determinations which 

 have been made by chemical means' and shows 

 the futility in such cases of the calculation of 

 the so-called probable error, a point which he 

 might well emphasize more strongly. 



In the chapters on liquids, the critical 

 state, and liquid mixtures Professor Young 

 deals with subjects to which his life has been 

 devoted. The reader expects therefore a com- 

 prehensive and stimulating treatment and he 

 is not disappointed. 



The introduction to physical chemistry by 

 Professor Eamsay which is included in this 

 book has already appeared in another volume 

 of the series. It is a very compact statement, 

 along conventional lines, of the historical de- 

 velopment of chemical theory. The reviewer 

 notes one paragraph, on solubility, page xxxv, 

 which may be very misleading to a beginner. 

 Gilbert IST. Levhs 



Behind the Scenes with the Mediums. By 

 David P. Abbott. Chicago, The Open 

 Court Publishing Co. 1906. Svo, pp. 328. 

 To the psychologist or layman interested in 

 the modus operandi of deception, this pains- 

 taking book by Mr. Abbott will prove as in- 

 valuable as it is interesting. It brings home 

 with renewed emphasis the technical expert- 

 ness that goes into the performances of the 

 modern mystifier, particularly of the type that 

 appeals to the spiritualistic or other pre- 

 possessions of the sitters. It emphasizes 

 equally how unevenly matched must be this 

 mystifier and the ordinary or even the extraor- 

 dinary investigator who interprets his in- 

 ability to discover how the effect is produced 

 into a warrant for the belief that something 

 defying natural experience has been witnessed. 

 In the face of such manifold and complex 

 procedures, the assurance of even the sincere 



