THE ATOMIC VIEW OF NATUEE. 



387 



there is however no difference of opinion on this point, 

 that since his time, and greatly through his labours, the 

 quantitative method has been established as the ultimate 

 test of chemical facts ; the principle of this method being 

 the rule that in all changes of combination and reaction, 

 the total weight of the various ingredients be they ele- 

 mentary bodies or compounds remains unchanged. The 

 science of chemistry was thus established upon an exact, 

 a mathematical basis. By means of this method Lavoisier, 

 utilising and analysing the results gained by himself and 

 others before him, notably those of Priestley, Cavendish, 

 and Black, succeeded in destroying the older theory of 

 combustion, the so-called phlogistic theory.-^ From a 



^ This result was aunounced in 

 1777 to the Paris Academy, and 

 the demonstration completed in a 

 memoir of 1783. " He closes this 

 latter memoir with the exiDi-ession, 

 that his object had been to bring 

 forward new proofs of his theory 

 of combustion of 1777, and to 

 l^rove that Stahl's phlogiston was 

 something purely imaginary, that 

 without it facts could be more 

 easily and more simply explained 

 than with it ; he did not expect 

 that his views would be at once 

 accepted, . . . time would have 

 to confirm or to reject the opinions 

 he had developed, but already he 

 recognised with satisfaction that un- 

 prejudiced students of the science, 

 unbiassed mathematicians and phy- 

 sicists, believed no longer in phlo- 

 giston as Stahl viewed it, and that 

 thejT considered the whole doctrine 

 more as a hindrance than as a help- 

 ful scaffolding in erecting the edifice 

 of science" (Kopp, ' Entwickelung,' 

 p. 202). This and the further re- 

 mark of Kopp that it was the 

 mathematicians who took up La- 

 voisier's views (see supra, p. 115, 



note 2) are significant signs of the 

 introduction of the mathematical, 

 the measuring, spirit into chemistrj^. 

 Few ideas which once exerted so 

 great and lasting an influence on 

 science as that of phlogiston, have 

 so entirely disappeared from our 

 text-books, and it is interesting to 

 note that those whose researches 

 were guided by it were not so far 

 from grasping a valuable truth 

 as has been supposed. This theory, 

 elaborated by Stahl, a contem- 

 porary of Newton and Leibniz 

 (1660-1734), was the first attempt 

 to co-ordinate a great mass of ob- 

 servations, to bring the phenomena 

 of chemical change under one com- 

 mon principle. Phlogiston was 

 the thing the migration of which 

 gave rise to chemical change, and 

 as the most obvious changes were 

 exhibited in the processes of com- 

 bustion, " Phlogiston" or " Brenn- 

 stofF" was the name which sug- 

 gested itself as most suitable for 

 this principle. Chemical changes 

 were not to be measured so much 

 by the resulting change of weight 

 as by the readiness with which 



