54 



NA TURE 



[November 15, 1900 



played a prominent part in supplying us with trust- 

 worthy guides, which afford the means of tracing to their 

 common origin many divergent lines of plant-evolution. 

 Among other genera which have thrown new light on the 

 course of evolution, the two Cycadofilicinean types 

 Heteratigium and Lyglnodendrojt, dealt with in Lectures 

 X. and xi., may be specially mentioned. 



It is impossible in a short review to deal adequately 

 with all the subjects of the lectures. A few remarks 

 might be made by way of criticism bearing on nomen- 

 clature and terminology, but this is a matter of secondary 

 importance. The work, as a whole, has been admirably 

 done ; its value is considerably enhanced by the fact that 

 many of the conclusions are founded on the author's 

 personal investigations which are characterised by ability, 

 thoroughness and sound judgment. It may be safely 

 said that there is no source from which the botanist can 

 gain so clear a view of the far-reaching importance of 

 researches into the morphology of Palaeozoic plants than 

 from the volume before us. A. C. S. 



PHYSICAL CHEMISTRY IN AMERICA. 

 The Journal of Physical Chemistry. Edited by Wilder 

 D. Bancroft and Joseph E. Trevor. (Cornell Uni- 

 versity, Ithaca, New York.) 

 'X*HE recent development of physical chemistry may 

 be said to date from the year 1887. The fundamental 

 ideas on which the modern superstructure rests had 

 been conceived and even published before that time ; but 

 though the phase rule of Gibbs, the osmotic pressure 

 theory of van 't Hoff and the electrolytic dissociation 

 theory of Arrhenius had all appeared in print, they were 

 buried in the little-known transactions of minor 

 academies, and so escaped general notice. It is un- 

 doubtedly to Ostwald that the popularisation of physical 

 chemistry is due. Himself an unflagging worker in the 

 field, he gathered together and systematised the work 

 done by his predecessors in the Lehrbuch der allgemeinen 

 Chemie, which was completed in 1886. In 1887 the new 

 era began with the establishment of his Zeitschrift fiir 

 physikalische Chemie. To the first volume of this 

 journal, van 't Hoff and Arrhenius contributed succinct 

 accounts of those theories which have since so largely 

 inspired and dominated physicochemical work. The 

 extent of this work may be gathered from the fact that 

 of the Zeitschrift thirty-four volumes have now been 

 published, each volume containing on the average nearly 

 750 pages. 



Amongst the students frequenting Ostwald's laboratory 

 in Leipzig there has always been a large number of 

 Americans, eager and energetic after their kind. Most 

 were enthusiastic for the new theories, and in the best the 

 enthusiasm was tempered by intelligent and judicious 

 criticism, differing widely from the suspicious conserva- 

 tism so often displayed in this country when these 

 theories have been under discussion. To this happy 

 scientific temperament we owe the fact that to-day 

 physical chemistry is being much more thoroughly culti- 

 vated on the other side of the Atlantic than in Britain. 

 In many, perhaps most, of the Universities it is taught 

 as part of the student's ordinary chemical equipment, and 

 the student who wishes to specialise in the subject can 

 NO. 1620, VOL. bi\ 



find in Boston or at Cornell ample opportunity and 

 encouragement for study and research. 



Cornell University has published since 1897 the. Journal 

 of Physical Chemistry under the editorship of two of its 

 professors. On the cover of the Journal for March 

 1899 we find that the department of chemistry offers the 

 following courses, each of which runs through the entire 

 year. 



(i) The Phase Rule. — A comprehensive qualitative 

 treatment of all types of chemical equilibrium, as these 

 are classified by the Phase Rule of Gibbs. 



(2) The Law of Mass Action. — Non-mathematical 

 exposition. 



(3) Mathematical Chemistry^ I. — The mathematical 

 theories of chemical equilibrium, of the velocities of 

 reactions, and of electrochemistry. 



(4) Mathematical Chemistry, II.— A systematic study 

 of Duhem's "Traite elementaire de Mecanique chimique." 



(5) The History of Thermodynamics.— ^s^tcx^]. con- 

 sideration is given to the physicochemical applications of 

 thermodynamic theory. 



(6) Introduction to Mathematical Chemistry. — An ele- 

 mentary exposition of the essential features of : {a) the 

 theory of surfaces, as applied in geometric representa- 

 tions of the thermodynamic properties of bodies ; {b) 

 spherical harmonics, as applied in the theory of 

 diffusion ; {c) the principles of least and varying action, 

 as applied to the problems of chemical and electro- 

 chemical equilibrium. 



(7) Electrochemistry. — Historical treatment. 



(8) The Velocities of Reactions. — Historical account 

 and mathematical theory. 



(9) Laboratory W^or/^.— Laboratory methods and ex- 

 perimental research. 



Two or three lectures weekly are given in each course, 

 the aggregate weekly number of lectures being twenty. 

 Certainly no German university offers a more complete 

 or systematic course of instruction in physical chemistry 

 than this. 



As might be expected from the countrymen of Gibbs, 

 the lecturers give a prominent place to the application 

 of thermodynamics to the problems of chemical equi- 

 librium. The same predilection appears in the Journal, 

 to which Duhem, the chief contemporary exponent of 

 the subject, is a frequent contributor. Electromotive 

 force also receives a large share of attention. The re- 

 views of books and critical abstracts of papers on 

 physical chemistry appearing in other publications are 

 in general well done, being brief, clear and to the point. 



The personality of one of the editors is deeply im- 

 pressed on the Journal. His views of the physical 

 chemistry of to-day may perhaps best be seen from the 

 following extract, taken from a notice of the new edition 

 of Ostwald's Grundriss der allgemeinen Chemie : — 



" Physical chemistry is not yet a quantitative science : 

 it is a pseudo-quantitative science. There are all the 

 outward signs of a quantitative science. We have 

 formulas and tables ; we make use of thermodynamics 

 and the differential calculus ; but this is for the most 

 part a vain show. Long before we reach the point where 

 the formula is to be tested experimentally, we slip in a 

 'simplifying assumption' ; that the concentration of one 

 component may be considered as constant ; that the heat 

 of dilution is zero ; that the solute may be treated in all 



