THE NEW CHEMISTRY. 395 



Thus chemists seemed obliged to imagine a something in addition 

 to the gross or ponderable matter of which bodies are composed, in 

 order to account for the properties of these bodies. As Science has 

 advanced she has been able to define what this something is ; at least, 

 she has defined it more clearly than the older workers could do. 



I havesaid, as Science has advanced she has defined the unknown 

 something ; but it should be remembered that that wonderful book, 

 which contains according to the greatest authorities the germs of 

 all our modern advances, was written sixty years before Lavoisier's 

 time. Sixty years before the apparent overthrow of the theory of 

 phlogiston, Newton had laid the foundations of the science which was 

 to reveal the true lineaments of that Unknown whom the phlogisteans 

 ignorantly worshiped. 



We have learned to extend the meaning of the word thing we 

 speak of " the power of doing work " as a measurable and definite 

 thing although not as matter : and we know that when a body burns 

 it loses a certain amount of this power of doing work, or, as it is more 

 shortly put, of energy. As usual, it is a question of words. The older 

 workers could not define phlogiston ; we are able to define energy, 

 and therefore we can see clearly where they saw but darkly. Chem- 

 istry now acknowledges that the properties of a compound are not only 

 determined by the composition of the matter of that compound, but 

 by the amount of energy associated with that collocation of matter. 

 She has been able to point out many instances of compounds composed 

 of the same matter, but possessed of different amounts of energy, and, 

 at the same time, of very different properties. And, moreover, chem- 

 istry aided by physics has concluded that the properties of a body 

 " are dependent on the variations of the energy of the body, and not 

 on its total value," and therefore that " it is unnecessary, even if it were 

 possible, to form any estimate of the energy of the body in its stand- 

 ard state." (I quote from that remarkable little book of the late 

 Professor Clerk Maxwell, " Matter and Motion.") 



Whenever Science made the advance from the vague conception 

 of " principles " and " imponderable matter " to the definite conception 

 of "mass," "motion," and "energy," she was able to recognize the 

 truth which lurked under the cumbersome and inexact nomenclature 

 of the phlogistean chemists. 



I have said that, as usual, the dispute between the phlogisteans 

 and their opponents was proved to be a question of meaning of words : 

 as usual, also, subsequent research showed that, while both were wrong, 

 both also were right. 



Composition is important, but composition is not all. The burned 

 body has properties differing from those of the unburned body, because 

 it has lost a certain amount of " the power of doing work " ; but it has a 

 less power of doing work because it is possessed of a structure differ- 

 ent from that which it possessed before. Composition and properties, 



