4o POPULAR SCIENCE MONTHLY 



least the attention should be directed to the fact that others draw dif- 

 ferent conclusions from the same premises. 



The average student is better able to face issues and weigh argu- 

 ments than most of us realize, and it is more important to educate 

 those falling below the average in this particular than in any other. 

 We should state the facts and then reason in such a way as to teach 

 students how to think. It is indispensable for them to learn to think 

 for themselves. Great stores of chemical facts are of but little real 

 use, unless accompanied by an ability to adapt and to apply them in 

 new conditions, unforeseen by either teacher or student in school or 

 university days, but surely coming in after life. It is the prime neces- 

 sity for research work or for originality of any kind, and we all are 

 willing to admit that originality is what should be cultivated. 



There is a great difference between the phrases, ' elements are sub- 

 stances which can not be broken up ' and ' elements are substances 

 which we have not as yet succeeded in breaking up ' ; and we should 

 mark well the difference. This caution, lest we slip into the error of 

 stating as fact more than we really know, is the distinguishing differ- 

 ence between the chemistry of to-day and the chemistry of a few years 

 ago. It is more than this, it expresses concisely the difference between 

 the way in which any science should be taught and studied, and the 

 way in which it should be neither taught nor studied. 



This particular differentiation between two definitions of the term 

 element has been more than justified by the results which have followed 

 the last ten years' work in pure chemistry, spectroscopy, radioactivity 

 and Eontgenology (a term which has been seriously proposed by one 

 of that fraternity which seems to consider its main function in life 

 to be the coinage of new words). 



The main arguments which may be marshaled in favor of consid- 

 ering the elements as ultimates, and the atoms as indivisible consist: 



First, of all those facts which Dalton condensed into the laws of 

 definite and multiple proportions, and to which there have been as 

 many additions as there have been analyses and syntheses made before 

 or since his time. 



Second, Dulong and Petit's law that the atomic heats of all solid 

 elements are the same. 



Third, the isomorphism of many compounds containing similar 

 elements, a phenomenon discovered by Mitscherlich. 



Fourth, Faraday's law, that equivalent quantities of the elements 

 are deposited at the electrodes during electrolysis. 



Truly, an imposing array of evidence, and more than sufficient to 

 justify us in making the assumption that atoms exist. But curiously 

 enough, there is not one item amongst all these facts compelling us to 

 believe that these atoms are the ultimate constituents, or that they are 

 indivisible. These latter hypotheses are purely gratuitous, tacked on 



