August 26, 1910] 



SCIENCE 



285 



fessor Traube contends, it has proved abso- 

 lutely sterile and unprofitable for advancement 

 of knowledge. Applied to the investigation 

 of concentrated or non-aqueous solutions,"" the 

 van't Hoff shibboleth pv = rt has become a 

 sort of scientific plaything, having yielded 

 hardly a single new fact of importance. The 

 return to a more chemical theory of solutions 

 signalized in Professor Kahlenberg's Boston 

 address'' was, therefore, inevitable and few will 



mental notions about osmotic and colloidal phe- 

 nomena. No one will impute this error of omis- 

 sion to either carelessness or insincerity; in all 

 probability. Professor Oswald's faith in the van't 

 Hoff formula is such that he sincerely believes 

 that the name of Graham is of no further impor- 

 tance in the history of chemistry. Yet no modern 

 chemist or physicist has got beyond Graham's 

 simple conception of osmosis as " the conversion 

 of chemical affinity into mechanical power." 

 (Phil. Tr., London, 1854, 227.) 



""Professor Kahlenberg relates that while work- 

 ing in the inspiring atmosphere of Ostwald's labo- 

 ratory in 1895, he asked the director why the 

 electrical conductivity of non-aqueous solutions 

 was not studied there, eliciting the genial reply: 

 " Die nicht-wasserigen Losungen leiten ja nicht ! " 

 (J.Phys. Chem., 1901, V., 341.) Professor Traube 

 likens the partizan of ionic dissociation to an 

 electrochemist who believes that the electrical 

 energy of a current depends more upon its in- 

 tensity than its electromotive force. Then he 

 points out that Arrhenlus assumes the ions in a 

 dilute solution to be at once electrostatically 

 bound but chemically unbound, although Faraday 

 and Helmholtz held the electrostatic and chemical 

 forces of the ions to be one and the same. (J. 

 PIiTjs. Chem., 1910, XIV., 475.) 



^ Professor Kahlenberg maintains that a solu- 

 tion is not a physical mixture but a chemical com- 

 position, differing from other chemical compounds 

 in degree but not in kind. It would seem prob- 

 able, from this argument, that the " gas-analogy " 

 of the van't Hoff-Arrhenius school confuses the 

 act of solution with the act of dilution, which at 

 oiice reduces the problem to the query: Is the 

 act of dilution (the solution of a watery solution 

 in water) the physical analogue of a mixture of 

 gases? Kahlenberg's view of osmosis is contained 

 in the following lucid statement : " The motive 

 power in osmotic processes lies in the specific at- 

 tractions or affinities between the liquids used. 



disagree with his opinion that " the efl^orts to 

 gain insight into the different solutions that 

 confront us must be chiefly experimental 

 rather than mathematical." It was a favorite 

 aphorism of Professor Huxley's that pages of 

 mathematical formulae will yield only chaff if 

 applied to loose or erroneous data and Syl- 

 vester, who believed that mathematics is an 

 experimental and inductive science, once 

 stated that he had published a number of 

 theorems which, when tested arithmetically, 

 proved to be untrue; but if a purely chemical 

 theory of solutions is to make much headway 

 and not be involved in fvirther obscurity, it 

 seems desirable that such indefinite, imagina- 

 tive concepts as " chemical attraction," " chem- 

 ical affinity " or " chemical potentiality " be 

 more clearly defined or differentiated. 



To illustrate the difficulty by returning to 

 Professor Traube's analogy, suppose chemical 

 substances to be represented by a number of 

 men and women of varying degrees of 

 strength of character and " attractiveness," 

 and suppose the marital combinations or 

 what Goethe called the " elective affinities " 

 between these men and women to be deter- 

 mind by certain mysterious " laws." If a 

 man strong in character should mate with a 

 woman, weaker but otherwise " attractive," or 

 vice versa, one set of observers might affirm 

 that the union was due to the man's superior 

 potentiality or masculinity, others might 

 maintain that the real strength in the combi- 

 nation or " affinity " lay in the woman's " at- 

 tractiveness " ; or vice versa. Curiously 

 enough, these anthropomorphisms, which 

 seem so plausible and fascinating in Goethe's 

 novel, are daily and hourly employed to ex- 

 plain the facts of chemical combination. 



The merit of Willard Gibbs's theory of phys- 

 ical chemistry lies in the fact that it does not 

 rest upon any fanciful anthropomorphisms nor 

 upon any theory (molecular or other) as to the 



and also those between the latter and the septum 

 employed. These attractions or affinities have also 

 at times been termed the potential energy of solu- 

 tion, etc. ; they are to the mind of the writer 

 essentially the same as what is termed chemical 

 affinity." {J. Phys. Chem., 1906, X., 208.) 



