194 



SCIENCE 



[N. S. Vol. XXXI. No. : 



most efficient training of chemists as tech- 

 nicians and as thinkers. 



Chemistry, it must be admitted, is still far 

 from being an exact science, but an enormous 

 stride has been made in this direction during 

 the last few decades as a result of the work of 

 such men as Guldberg and Waage, Gibbs, 

 van't Hoff and Arrhenius. The exact laws 

 and theories developed during this period con- 

 stitute powerful weapons of research which 

 are the birthright of the new generation of 

 chemists. To withhold all laiowledge of these 

 illuminating ideas even in the most elemen- 

 tary course in chemistry is unjust to the stu- 

 dent and to the science. 



If the author had omitted all theory from 

 his book and made it frankly descriptive, 

 there would be little to criticize and much to 

 praise, but this volume contains fully as 

 much of chemical theory as the average 

 teacher would consider it desirable to intro- 

 duce in a single course. However, the laws 

 and theories with which the reader of Kahlen- 

 berg's book will become familiar are chiefly 

 limited to those which had been accepted a 

 generation or more ago. 



It was to be expected from one holding 

 Professor Kahlenberg's pronounced views that 

 the great modern developments in the study 

 of solutions, especially of aqueous solutions 

 of electrolytes, would receive but scant atten- 

 tion, but other great advances in chemical 

 theory suffer from an equal neglect. The im- 

 portant ideas of heterogeneous equilibriimi 

 introduced by Willard Gibbs, which have been 

 brought into simple pedagogic form by vari- 

 ous teachers, notably by Ostwald, are not only 

 ignored, but statements are made which 

 flagrantly violate all phase-rule doctrine. The 

 student can not fail to acquire fundamentally 

 erroneous conceptions from such a paragraph 

 as the following : 



Suppose a block of ice and one of common salt 

 be placed in contact with eacli other; we note 

 that the salt and ice gradually disappear, forming 

 a brine. Evidently the brine has quite different 

 properties from those of either the salt or the ice. 

 Moreover, there was a marked change of tempera- 

 ture, in this case a cooling effect, as the salt and 

 ice acted on each other. Purthermore, a contrac- 



tion ensued, for the volume of the brine is less 

 than the sum of the volumes of the blocks of ice 

 and salt. Again, as a block of ice and one of 

 paraffine, or one of salt and one of paraffine, for 

 example, do not act on each other at all when 

 brought into contact, it is clear that the action 

 between ice and salt takes place because of the 

 specific nature of the substances. Furthermore, 

 it has been found that below — 22° C. ice and 

 common salt no longer act on each other, just as 

 iron and sulphur do not act on each other at 

 ordinary temperatures. Raise the temperature 

 suificiently in each case, and at a certain definite 

 point action begins. 



In this paragraph the author shows also his 

 attitude towards the important subject of re- 

 action velocity. His comparison of the eutec- 

 tic point of salt and water with the " definite 

 point " at which sulphur and iron begin to 

 react might be regarded as a mere slip of the 

 pen were it not for the fact that similar ideas 

 are advanced in the discussion of ignition 

 points and kindred phenomena. One of the 

 most serious fallacies concerning reaction 

 velocity is not only affirmed but italicized on 

 page 23. 



The rate with which a chemical reaction pro- 

 ceeds is proportional to the chemical affinity that 

 comes into play. 



If this were the truth we may be sure that 

 none of us would be alive to announce it, for 

 the affinity of our tissues for the oxygen of the 

 air is enormous compared with that which 

 comes into play in the majority of vital proc- 

 esses. 



Other instances of too much theory might 

 be cited. Por example, the statements con- 

 cerning the nascent state and the mechanism- 

 of oxidation and reduction processes are, to 

 say the least, unproven. In discussing inor- 

 ganic compounds frequent use is made of 

 graphical formulae of very questionable char- 

 acter. Mention is nowhere made of the simple 

 gas laws, but an amazing polemic chapter is 

 devoted to theories of solution and osmotic 

 pressure. 



The principle of mass action is given 

 friendly though somewhat scant discussion. 

 Owing to the author's unwillingness to adopt 

 the ionic view, he has been unable to apply 



