724 



SCIENCE. 



[N. S. Vol XII. No. 306. 



addition to the orthodox chemistry the student 

 learns about many things which are ordinarily 

 included in a special course on physical chem- 

 istry : rate of diffusion, reversible equilibrium, 

 mass action, catalysis, phase rule, thermochem- 

 ical relations, dissociation theory, electrolysis 

 and Faraday's law, free energy, theorem of 

 LeChatelier, strength of acids, relation of mon- 

 otropic and enantiotropic forms, hydrolysis, 

 reaction velocity. 



The dissociation theory is introduced in a 

 very natural way. It is first shown that the 

 hydrogen of an acid differs from the hydrogen 

 of other compounds in that it always shows the 

 same reactions quite irrespective of the nature 

 of the acid radical. Certain other properties 

 are characteristic only of the hydroxyl of bases 

 and are further independent of the basic rad- 

 ical. All soluble chlorides react with silver 

 nitrate to form silver chloride. The radical 

 whose reactions are independent of the other 

 radical forming the salt is defined as an ion, 

 and the characteristic properties of these ions 

 are then discussed. It is then shown that salts 

 are electrolytes, and that the ions of chemistry 

 are also the ions of electrolysis. 



There is no question but that this book is the 

 official sign of the beginning of a new era in 

 teaching introductory chemistry. Hitherto 

 physical chemistry has been an independent 

 branch of chemistry rather tlian the science of 

 chemistry. While physical chemistry has ex- 

 erted an infiuence upon elementary, analytic, 

 inorganic, and organic chemistry, this has been 

 an influence from without. An occasional fact 

 has been worked into the frame here, an open- 

 ing for a new view has been made there ; but 

 this has been a case of patching old garments in 

 a vain attempt to keep them decently present- 

 able. It is evident that the whole teaching of 

 chemistry must be put on a new basis and car- 

 ried on along scientific lines. This has been 

 done for elementary chemistry in the book now 

 under discussion, and it is now possible for 

 those teaching introductory chemistry to pre- 

 sent their subject in a satisfactory way, even 

 though they may not themselves have been 

 trained in physical chemistry. 



The time is ripe for such a change. Ostwald 

 has been working up to it for j^ears. In this 



country, as well as in Europe, there are uni- 

 versities and colleges where lectures on element- 

 ary chemistry are now being given by physical 

 chemists along similar, though not identical, 

 lines. Holleman has recently published a text- 

 book which may be looked upon as a forerunner 

 of Ostwald's volume. While the reviewer is not 

 so sanguine as to expect that Ostwald's book 

 will be adopted at once throughout the length 

 and breadth of the scientific world, yet the 

 time is surely coming when the right way of 

 teaching the subject will be the general way. 

 The fact that this book will revolutionize the 

 whole teaching of introductory chemistry is a 

 striking illustration of Ostwald's ability as an 

 expounder. Ostwald has done much brilliant 

 scientific work ; but his real strength is as a 

 teacher. It is not an exaggeration to say that 

 the first edition of his Lehrbuch created the 

 science of physical chemistry. Horstmann had 

 had a glimpse of the promised land ; but it was 

 Ostwald who led the chemists into it. Van't 

 Hoff originated the modern theory of solutions, 

 Arrhenius the theory of electrolytic dissocia- 

 tion, and Nernst the osmotic theory of the 

 voltaic cell ; but it is Ostwald who has de- 

 veloped these theories and who has forced their 

 acceptance. It is to Ostwald that we owe the 

 rejuvenation of analytical chemistry and we 

 now owe to Ostwald by far the best text-book 

 on introductory chemistry. 



Wilder D. Bancroft. 



Twelfth Annual Report on the Railways of the 

 United States, for the year ending June 30, 

 1899. By the Statistician to the Interstate 

 Commerce Commission. Washington, Gov't 

 Print. 1900. 8vo. Pp. 712. 

 It is unfortunate that some such system as is 

 employed by the Census Bureau, adapted to 

 this special line of work, cannot reduce the 

 period of waiting for these reports. The Com- 

 mission dates its report for the year ending 

 June, 1899, precisely one year later than that 

 date and the shortening of this delay and wait- 

 ing would have value in high ratio with the 

 proportion by which the period of delay 

 might be reduced. Undoubtedly the Commis- 

 sion and its employees do their best, however, 

 and we must hope for some later Hollerith to 



