I 



THE PHLOGISTON THEORY IN CHEMISTRY 



THE development of the science of chemistry from 

 the "science" of alchemy is a striking example 

 of the complete revolution in the attitude of observers 

 in the field of science. As has been pointed out in a pre- 

 ceding chapter, the alchemist, having a preconceived 

 idea of how things should be, made all his experiments 

 to prove his preconceived theory; while the chemist 

 reverses this attitude of mind and bases his concep- 

 tions on the results of his laboratory experiments. In 

 short, chemistry is what alchemy never could be, an 

 inductive science. But this transition from one point 

 of view to an exactly opposite one was necessarily a 

 very slow process. Ideas that have held undisputed 

 sway over the minds of succeeding generations for 

 hundreds of years cannot be overthrown in a moment, 

 unless the agent of such an overthrow be so obvious 

 that it cannot be challenged. The rudimentary chem- 

 istry that overthrew alchemy had nothing so obvious 

 and palpable. 



The great first step was the substitution of the one 

 principle, phlogiston, for the three principles, salt, sul- 

 phur, and mercury. We have seen how the experi- 

 ment of burning or calcining such a metal as lead " de- 

 stroyed" the lead as such, leaving an entirely different 



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