NATURE 



241 



THURSDAY, JULY 12, 1906. 



VUXSICAL CHEMISTRY APPLIED TO 

 CHEMISTRY AND BIOLOGY. 

 Coiirs dc Chimie physique, suivi d' Applications a la 

 Chimie et a la Biologic. By Victor Henri. Cours 

 libri" professe i la Faculty des Sciences de Paris. 

 Premier Fascicule. Pp. xii + 336 et seq. (Paris: 

 .\. Hermann, 1906.) Price 15 francs. 



TIII.S volume forms a portion of the first part of a 

 treatise on physical chemistry and its applications 

 to chemistry and biology, evidently intended for readers 

 commencing the specialised study of physical chem- 

 istry, but possessing some considerable knowledge of 

 chemistry and biology. 



']"he subjects described in the thirteen chapters of 

 this first part are as follows : — General conditions of 

 equilibrium in solutions; electrical conductivity of 

 solutions; ionic theory; conductivity in non-aqueous 

 solutions; osmosis and osmotic pressure; diffusion; 

 crvoscopv; vapour pressure and boiling-point of solu- 

 tions ; absorption and solution ; solubility and co- 

 efficient of distribution in solution ; surface tension 

 and viscosity of solutions; optical properties of solu- 

 tions; electrical phenomena in solutions, study of 

 galvanic and concentration cells (incomplete). 



The general scheme of treatment which the author 

 outlines in his preface consists in describing in each 

 case (1) the methods of measurement used in study- 

 ing the particular phenomenon under consideration, 

 (2) the experimental results obtained, and (3) the 

 hypotheses and general theories which make it pos- 

 sible to connect together the experimental results and 

 ,ilso others obtained by different experimental methods. 

 This method of presenting experimental results apart 

 from the theory which may have given birth to the 

 observ'ations, or have formed a connecting link for 

 correlating them with other known facts, may be 

 most philosophical, and occasionally most desirable, 

 in order to impress upon the mind of the student 

 that the observed facts exist apart from anv theory, as 

 has been most ably done by the present author, for 

 example, in chapters i., ii., and iii. of his treatise. At 

 the same time it can and does become a most 

 cumbrous and space-robbing form of description, and 

 much beauty is lost by not placing the facts at once 

 in the appropriate setting of the theory which lead 

 the mind to the planning of the experimental work 

 which established the fatts. 



It is no doubt quite possible that a mathematical 

 treatise might be written without the use of any 

 symbols or any conventions of any type, or that a 

 treatise on chemistry might be written consisting of 

 bare, dry experimental facts without any reference 

 to the atomic theory. Such treatises would be most 

 interesting as monuments of human perseverance 

 and industry, and would be literary curiosities of the 

 highest order; but it is questionable if they would 

 be very intelligible, and certainly they would be very 

 lengthy, and most unstimulating to the student or 

 worker, who could not proceed a step further with 

 their aid alone in the way of advance, but would at 

 NO. 191 5, VOL. 74] 



once have to proceed to formulaic a theory if it were 

 desired to carry out an experiment differing in type 

 from any in such a non-theoretical treatise. Without 

 .1 theory in advance there can be no such thing a 

 intelligent experimentation ; after experimentation, 

 the theory must be adapted where necessary to ex- 

 perimental results, or, if necessary, a new theory 

 formulated which will lead to further experimentation. 



It is therefore a relief to find that after the first 

 three chapters the author somewhat alters his plan, 

 accepts the ionic theory, and speaks boldly of ions. 

 Some of the aspects in which the ionic theory, as at 

 present held, fails to account for experimental facts 

 are pointed out in the book, and those many experi- 

 mental observations which arc accounted for, and 

 correlated, by the theory are justly held up for well- 

 deserved admiration. 



The author is also to be congratulated upon not 

 having too thoroughly carried out the intention ex- 

 pressed in his preface of making the mathematics 

 of physical chemistry problems easy for the non- 

 mathematical reader. 



The authors who invent and perpetuate this style 

 of mathematics made easy surely forget that a reader 

 who has not a rudimentary notion of how to apply 

 the calculus probably has not learnt his more ele- 

 mentary mathematics well enough to follow the solu- 

 tion of their long and involved series and equations, 

 and if he ever did has probably forgotten it long 

 ago, and therefore skips the proof and accepts the 

 conclusion much as he would have done had the 

 proof been given in the shorter way. 



.As stated above, anything which can be put or 

 proven in mathematical symbols could also be equally 

 put or proven in ordinary words, provided patience 

 and perseverance could be provided on the part of the 

 author to write it, and of the reader laboriously to 

 wade through it; but when there is a better method, 

 surely it is much better for the non-mathematical 

 reader to accept his mathematics ready made for 

 him, or, if he objects to doing this, take up the 

 study of mathematics a little longer and then turn 

 to its applications. 



It is accordingly a relief to find that the author does 

 not carry his threat of making mathematics easy too 

 far, and employs the calculus where necessary. 



Regarding the subjects treated in the first part 

 so far as they are contained in the present volume, 

 it may be said that on the whole the style of treat- 

 ment is most interesting, and the information usually 

 full and carried well up to the present date. 



Occasionally it would have been well, as the work 

 is obviously intended specially for biological students 

 interested in physical chemistry, if the biological 

 aspects had been treated at greater length, as, for 

 example, in the section on the theory of indicators 

 on p. no, and that on the study of the fluids of the 

 organism, p. 114; but it is possible that the author 

 may intend to return to these subjects at a later part 

 of the work. 



The descriptions of how to carr\- out experimental 

 work given in the volume are clearly intended to 

 enable the student to carry on experiments, for the 



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