30 HISTORY OF CHEMISTRY. [LECTURE II. 



water, and how this process, which he properly classes as one 

 of combustion, furnishes to man the heat necessary for his 

 existence. 44 He demonstrates that the expired carbonic anhy- 

 dride derives its carbon from the blood itself; that in the pro- 

 cess of respiration we thus, to a certain extent, burn ourselves, 

 and would consume ourselves if we did not replace, by means 

 of our food, that which we have burned. Since he next finds, 

 by special experiments, that in strained activity the breathing 

 is hastened, and that the consumption of carbon is thereby 

 increased, he arrives at the conclusion that the poor man, com- 

 pelled as he is to work, consumes more carbon than the indolent 

 rich man ; but that the latter, by an unfortunate circumstance 

 in the division of worldly possessions, can satisfy his smaller 

 requirements and that too by means of better food much 

 more readily than the poor workman can. He therefore calls 

 upon society to remedy this evil by means of its institutions, to 

 improve the lot of the poorer classes, and in this way to smooth 

 away, as far as possible, those inequalities which apparently are 

 established in nature. He closes this ingenious treatise with 

 the words : 45 



" It is not indispensable, in order to deserve well of humanity, 

 and to pay his tribute to his country, that a man should be 

 called to those public and pompous functions which co-operate 

 in the organisation and regeneration of empires. The physicist, 

 in the quiet of his laboratory and of his study, can also exercise 

 patriotic functions ; he can hope to diminish by his labours the 

 many ills which afflict the human species, and to increase 

 human pleasures and prosperity. And if he should only con- 

 tribute, by the new methods which he may have shown, to the 

 lengthening of the mean age of man by a few years, or even by 

 a few days, he also may aspire to the glorious title of benefactor 

 of humanity." 



His own time rewarded him badly for his endeavours. 

 Four years later, in 1794, he was guillotined by order of the 

 Revolutionary Committee. 



44 Lavoisier, Oeuvres, 2, 331. 45 Ibid. 2, 703. 



