NA TURE 



241 



THURSDAY, JANUARY 12, iJ 



PHYSICAL CHEMISTRY. 



Lehrbuch ckr Allgemeinen Chcmie. Von Dr. Willi. 

 Ostwald. In Zwei Banden. (Leipzig : W. Engelmann, 

 1885-87.) 



THE larger text-books of chemistry have generally 

 been devoted to describing and roughly classifying 

 the facts which form the foundation of the science. 

 These facts are so numerous, varied, and important, that 

 when one has spent years in arranging, cataloguing, and 

 reciting them, his chemical vision has generally acquired 

 a fixed downward direction, and he is almost unable to 

 lift his eyes from the foundation-stones to look on the 

 buildings which other workers have been raising. 



But, whether such a one will look at the building or 

 not, the building is surely rising. The walls already are 

 massive ; there are adornments of conceits, perhaps 

 sometimes too quaint ; windows there are in plenty to 

 admit light and air : the house will never oe completed, 

 because nature is inexhaustible, but even now there is 

 promise of a goodly building. Nor shall the House 

 Beautiful want fit interpreters, among whom an honour- 

 able place will be held by the Professor of Physical 

 Chemistry at Leipzig. 



It has generally been admitted that chemistry is a 

 branch of physical science. Individual chemists by their 

 researches have shown that the relation of chemistry to 

 physics is that of the less to the greater ; but most of the 

 attempts to set forth this relationship in its entirety have 

 failed. To treat chemistry as a branch of physics 

 requires one who is almost as much a physicist as a 

 chemist, but one whose physical training has waited on 

 his chemical judgment. Some books on physical 

 chemistry have been books on descriptive chemistry, with 

 scraps of physical facts thrown in ; others have been 

 books on physics to which the use of chemical illustra- 

 tions has given an ill-defined but not unpleasing chemical 

 tone. Only of late years has it become possible to set 

 forth the connections between the parent science and the 

 greatest of her children in a fairly satisfactory manner ; 

 and this possibility has come through the recent advances 

 made in the study of these connections. 



It was therefore fitting that one of the men whose 

 work forms no small part of all of first-class importance 

 that has been done in recent years in the sphere of physical 

 chemistry should be the man to write the first good text- 

 book on general chemistry considered as a branch of 

 physics. Ostwald prefers to call his work " Lehrbuch der 

 Allgemeinen," rather than "physikalischen," " Chemie." 

 The title very happily expresses the scope and character 

 of the book ; but the treatment of chemical principles 

 in a general manner is made possible in this treatise 

 by regarding chemistry as a special branch of physics. 

 The book is intended for fairly advanced students who 

 have already a tolerable knowledge both of descriptive 

 chemistry and of physical principles. Some of the higher 

 forms of mathematical analysis are freely employed. 

 The form in which the author has chosen to present his 

 treatise is the historical-critical ; he justly remarks that 

 Vol. XXXVII. — No. 950. 



the historical coincides with the logical development of 

 many chemical ideas. 



As the object of the work is to enable the student to 

 gain a firm hold of the principles of chemistry, and more 

 especially to teach him that very many of these principles 

 have been reached by the application of physical methods 

 to chemical phenomena, much care is taken to distinguish 

 generalized statements of facts from hypotheses, to 

 indicate the need of using hypotheses, to trace the 

 merging of several hypotheses into one general theory, 

 and to avoid mere speculation. 



Th^ first volume is devoted to stochiometry. The laws 

 of chemical combination, which form the basis of the 

 whole science, are laid down in a singularly clear and 

 succinct manner ; the atomic theory of Dalton is 

 sketched ; the chemical methods by which combining 

 weights are determined are classified, and this is followed 

 by a short critical exposition of the results obtained for 

 each element. The second, third, and fourth books of the 

 first volume are devoted to accounts of the properties of 

 gaseous, liquid, and solid bodies, respectively. The 

 relations between the volume, temperature, and pressure 

 of gases, are considered ; this leads to a statement of 

 the law of Gay-Lussac, and a consideration of Avogadro's 

 hypothesis ; then follows an account of the kinetic theory 

 of gases, the specific heats, and the optical properties of 

 gases. The book on liquid bodies is devoted to a con- 

 sideration of (i) the general properties of liquids ; (2) 

 the relations between the liquid and gaseous states ; (3) the 

 volume-relations of liquids ; (4) solution ; (5) optical 

 properties of liquids ; (6) capillarity, diffusion, and 

 osmosis ; (7) electrical conductivities and electrolysis of 

 liquids ; (8) specific heats of liquids. The book on the 

 stochiometry of solid bodies includes the consideration 

 of crystallography, especially in its chemical bearings, the 

 optical and electrical properties of solids, &c. The first 

 volume concludes with a sketch of the relations between- 

 atomic weights and chemical properties, a general account 

 of the molecular theory as applied in chemistry, and a 

 short but very suggestive chapter on theories of chemical 

 composition and constitution. 



The second volume deals with the vast and widely- 

 ramifying subject of chemical affinity. The first part, on 

 chemical energy, comprises what is really a comprehen- 

 sive treatise on thermo-chemistry, and also full critical 

 accounts of photo-chemistry and electro-chemistry. The 

 second part, dealing more distinctly with chemical 

 affinity, begins with an historical sketch ; this is followed 

 by about 150 pages on chemical dynamics ; and the whole 

 concludes with an account of the various methods whereby 

 measurements of the relative affinities of various bodies, 

 especially acids and bases, have been obtained ; the last 

 chapter deals with the relations between the nature, com- 

 position, and constitution of bodies, and the values of 

 their affinity-constants. 



Ostwald has undertaken and brought to a conclusion a 

 task of great difficulty. His book has removed the sting 

 froni the taunt so often cast at the chemist that chemistry 

 is the pursuit of the mere fact-finder and formula-monger. 

 If Ostwald's " Lehrbuch" had only made evident the fact 

 that chemistry is one of the exact sciences it would have 

 done much ; but it has done more than this ; it is a 

 repository of the general and abstract truths of the 



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