LAVOISIER. 329 



and it is no small proof of his merit, that for many 

 years he remained almost alone among the philoso- 

 phers of his age, and even his own countrymen, how 

 prone soever to adopt French discoveries, in maintain- 

 ing opinions from which there is now, after the lapse 

 of little more than half a century, not a single dissent- 

 ing voice all over the scientific world. 



We are now to mark wherein he was led astray by 

 the love of theorising carrying him too far. He was 

 not content with showing that combustion, contrary to 

 the phlogistic doctrine, proceeds from a union of the 

 burning body with other bodies ; but he regarded the 

 body uniting as always the same, to wit, oxygen. Ob- 

 serving the fact of many bodies burning in oxygen gas, 

 and of most other gases being unfit for supporting flame, 

 he generalized too much, and inferred that all combus- 

 tion consists in the union of that gas with the inflam- 

 mable body. Again : he regarded the heat and light 

 given out in the process as wholly proceeding from the 

 gas, as having kept the gas when latent in its aeriform 

 state, and as given out in a sensible form when the gas 

 becomes fixed in a liquid or a solid state. Lastly : ob- 

 serving that the union of many bodies with oxygen 

 produced acids, he generalized too much this fact, and 

 inferred that all acids contain oxygen, which he thence 

 called by that name, as denoting the acidifying princi- 

 ple. Now all these inferences are groundless, and there- 

 Fore this portion of his theory is to be rejected. He 

 is to be followed implicitly in rejecting Stahl's princi- 

 ple ; the doctrine of phlogiston he for ever overthrew. 

 His own theory, the doctrine which he substituted in 

 place of the one which he had destroyed, is liable to 

 insuperable objections; at least when carried to the 

 length which he went. 



In the first place, not only may oxygenation take 

 place without any evolution of either heat or light, but 

 combustion also. The mixture of many substances 

 together evolves heat, and a great degree of heat, with- 



