M. Dumas on the Chemical Statics of Organized Beings. 467 



It is evident to me that all animal heat arises from respira- 

 tion; that it is measured by the carbon and hydrogen burnt. 

 In a word, it is evident to me that the poetical comparison of 

 a rail-road locomotive to an animal is founded on a more se- 

 rious basis than has perhaps been supposed. In each there 

 are combustion, heat, motion, three phaenomena connected 

 and proportional. 



You see, that thus considering it, the animal machine be- 

 comes much easier to understand; it is the intermediary be- 

 tween the vegetable kingdom and the air ; it borrows all its 

 aliments from the one, in order to give all its excretions to 

 the other. 



Shall I remind you how we viewed respiration, a pheno- 

 menon more complex than Laplace and Lavoisier had thought, 

 or even Lagrange had supposed, but which precisely, as it 

 becomes complicated, tends more and more to enter into the 

 general laws of inanimate nature? 



You have seen that the venous blood dissolves oxygen and 

 disengages carbonic acid ; that it becomes arterial without 

 producing a trace of heat. It is not then in becoming arterial 

 that the blood produces heat. 



But under the influence of the oxygen absorbed, the soluble 

 matters of the blood change into lactic acid, as MM. Mit- 

 scherlich, Boutron-Charlard and Fremy observed ; the lactic 

 acid is itself converted into lactate of soda ; this latter by a real 

 combustion into carbonate of soda, which a fresh portion of 

 lactic acid decomposes in its turn. This slow and continued 

 succession of phaenomena which constitutes a real combustion, 

 but decomposed at several times, in which we see one of the 

 slow combustions to which M. Chevreul drew attention long 

 ago, this is the true phenomenon of respiration. The blood 

 then becomes oxygenized in the lungs ; it really breathes in 

 the capillaries of all the other organs, there where the com- 

 bustion of carbon and the production of heat principally 

 take place. 



A last reflection. To ascend to the summit of Mont-Blanc, 

 a man takes two days of twelve hours. During this time, he 

 burns at an average 300 grammes of carbon, or the equivalent 

 of hydrogen. If a steam-engine had been employed to take 

 him there, it would have burnt from 1000 to 1200 to accom- 

 plish the same work. 



Thus, viewed as a machine, borrowing all its power from 

 the coal that it burns, man is an engine three or four times 

 more perfect than the most perfect steam-engine. Our en- 

 gineers have therefore still much to do, and yet these num- 

 bers are quite such as to prove that there is a community of 



2H2 



