168 THE ANATOMY OF SCIENCE 



the phlogiston theory would never have fallen 

 into disrepute. Indeed, it is curious now to note 

 that not only their new classification but even 

 their mechanism was essentially correct. It is 

 only in the last few years that we have reahzed 

 that every process that we call reduction or 

 oxidation is the gain or loss of an almost im- 

 ponderable substance, which we do not call 

 phlogiston but electrons. 



The art of weighing brought into chemistry 

 a quantitative, and therefore mathematical, ele- 

 ment. The discovery of the law of multiple pro- 

 portions led Dalton to his atomic theory. I shall 

 not dwell upon the modern development of this 

 idea in the hands of chemists and physicists, 

 nor show how the atom has been brought closer 

 and closer into our field of vision, so that we 

 have been able to dissect it into its component 

 parts. Many details of our atomic picture may 

 still be erroneous, but concerning its cardinal 

 features most scientists are now agreed. 



It may, however, be instructive to compare 

 the methods by which physicists and chemists 

 have attacked this problem. The physicist starts 

 with a small number of measurements, which, 

 however, are of the highest accuracy. He finds 

 an equation which will fit these measurements 



