272 LAVOISIER, 



fixed in a liquid or a solid state. Lastly : observing 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 principle. Now all 

 these inferences are groundless, and therefore this portion 

 of his theory is to be rejected. He is to be followed 

 implicitly in rejecting Stahl's principle ; 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. The mixture of many substances together 

 evolves heat, and a great degree of heat, without the 

 presence of oxygen or if oxygen be present in some of 

 these cases, it is not operative in any way it is not 

 disengaged, and is not in the form of a gas to be ab- 

 sorbed. Thus, much heat is caused by the mixture of 

 sulphuric acid and water; some heat by the mixture 

 of alcohol and water. Lime when slaked by water 

 produces violent heat, sometimes accompanied with light 

 also, flame as well as redness appearing. The union of 

 iron with sulphur in vacuo causes great heat and the 

 emission of bright light. The exposure of metals and 

 other inflammable bodies to gases which contain no 

 oxygen, as chlorine, produces red heat and flame. There- 

 fore, although it is very true that we know of no instance 

 in which combustion takes place without the union of 

 the combustible body to some other, and the formation 

 of a new substance, yet it is not true that oxygen alone 



