Many scientific advances depend on the obstacles that have been solved by predecessors. At this time, when a person with a specific perspective, background and research skills happens to appear, he or she has a chance to stand out. Lavoisier, a scientist who has made great achievements in other fields of chemistry, has such good luck when facing the problem of breathing, because all the obstacles that must be solved have been taken down in front of him: Harvey explained the blood circulation and expounded the breathing movement; Marby base completed the microscopic anatomy of the lung; As for gas chemistry, it is partly because of his own efforts that he has made unprecedented progress. By the end of 18, the gas was successfully separated and identified, which triggered a chemical revolution. Now we can finally start to study the breathing problem.

By 1777, lavoisier published a paper entitled "Animal Breathing Experiment and Changes of Air Passing through Lung". At this time, he has realized that breathing involves two different gases, one is "air especially suitable for breathing" (oxygen) and the other is "fixed air" (carbon dioxide)-lavoisier interpreted breathing as a slow combustion or oxidation process. Although his British colleague priestley failed to grasp this point, lavoisier grasped the key point. Breathing is the process of using oxygen and releasing carbon dioxide. In cooperation with Laplace, he designed an experimental device, which can quantitatively measure the heat production of animals to study the physical and chemical basis of respiration. Using their improved calorimeter, breathing and combustion can be quantitatively compared and exciting results can be obtained. The analogy between breathing and burning is no longer just a beautiful metaphor. Lavoisier can now draw such a conclusion in his essay "Thermology": "The heat released when pure air is converted into fixed air during breathing is the main reason for maintaining animal heat."