976 



SCIENCE 



[N. S. Vol. XXVII. No. 704 



midway between chemistry and physics, 

 and helpful to both. We are in the era of 

 ions. It took chemists many years to learn 

 to use the words atom and molecule in a 

 rational way. Now that they have learned 

 this lesson fairly well, the ion has come in 

 to plague them and— to help them. Here 

 again it must be remembered that the ion 

 is no new thing. Indeed we owe the word 

 and the first conception to Faraday. But 

 Arrhenius has emphasized its importance 

 in connection with reactions that take place 

 in solution and we have fallen captive. 

 So thoroughly have we yielded to its influ- 

 ence that we are now using the ion as food 

 for babes. It is an exception now-a-days 

 to find one who has studied chemistry a 

 few weeks who wiU not discourse at length 

 on ions. Do not misunderstand me. I 

 acknowledge gladly the great impetus that 

 has come to chemistry through the concep- 

 tions of dissociation and ions, but I do 

 question the desirability of attempting to 

 introduce these conceptions at too early a 

 period in the teaching of chemistry. The 

 result must inevitably be dogmatic teach- 

 ing and dogmatic teaching is not scientific 

 teaching. 



The development of physical chemistry 

 has not interfered with the study of con- 

 stitutional chemistry or of any other 

 branch of chemistry, but has made it pos- 

 sible to interpret many phenomena more 

 satisfactorily than formerly. The result 

 of the application of physical methods to 

 the study of chemical phenomena has been 

 to give us more refined views and deeper 

 insight. It is idle to claim that one method 

 of investigation is higher than another. 

 As Professor Nernst has recently said: 

 ' ' The question whether chemistry has prof- 

 ited most by the atomic theory or by ther- 

 modynamics is a foolish one. It is like the 

 question whether Goethe or Schiller is the 

 greater poet. Let us rejoice that we have 

 two such poets. Let us rejoice that we 



have two such valuable methods of chem- 

 ical research. We need all the aid we can 

 possibly get and even with this aid prog- 

 ress will be relatively slow." 



The latest developments in chemistry are 

 in some respects the most remarkable of all. 

 A recent writer has said : ' ' The ideas which 

 guide chemists when they use the molecular 

 and atomic theory, when they apply the 

 periodic law, when they deduce composi- 

 tion from crystalline form, when they use 

 the hypothesis of ionization, when they dis- 

 cuss certain aspects of chemical affinity, 

 when they connect changes of composition 

 with changes of energy; these and many 

 other guiding ideas are the gifts of the 

 physicist to the chemist. The measure has 

 been returned by the chemist 'pressed 

 down and running over.' By the discov- 

 ery of radium the chemist has called a new 

 world into being; and, with a fine gener- 

 osity, he has given it to the physicist to 

 investigate." The study of radium and 

 similar elements has led to most unexpected 

 results of fundamental importance which 

 have already thrown much needed light on 

 the constitution of matter and have made 

 it appear probable that electric charges, 

 whatever they may be, are responsible for 

 all forms of matter as well as for some 

 forms of energy. But the statement that 

 matter is made up of electric charges, how- 

 ever soothing it may be, raises the question 

 what is an electric charge?— a question as 

 difficult to answer as the older one, what is 

 matter? Everything then resolves itself 

 into electricity. Truly, "The old order 

 changeth, yielding place to new. ' ' But not 

 so fast. What we call matter still exists 

 and the old phenomena presented by it still 

 call for study, and wiU through eternity. 



Let us finally return to the earth for a 

 moment. Leaving out of consideration the 

 theories that have grown out of the study 

 of radioactivity, let us note the conclusion 

 that has been forced upon us that the atom 



