ANIMAL HEAT. 393 



extend our work to an unreasonable size. Besides this, it is still 

 questionable whether the theory of animal heat, which embraces 

 so many purely physical and purely physiological laws and facts, 

 can, strictly speaking, be considered as pertaining to physiological 

 chemistry ; for, if we admit its claim to this rank, we might with 

 equal justice be called upon to enter into a more detailed expo- 

 sition of the theory of animal electricity, since this, no less than 

 the theory of animal heat, is based upon chemical inquiry. We 

 ought to observe, however, that the special heat of every animal 

 organism is merely the result of chemical combinations formed 

 within it. No one has elaborated this proposition with more 

 argumentative ingenuity and ability than Liebig ; and nothing but 

 excessive incredulity, combined with an inadequate knowledge of 

 physical laws, could lead any one to doubt the correctness of his 

 exposition. Dulong* and Despretz*^ are, however, almost the 

 only inquirers who have afforded us any positive investigations in 

 relation to the main point of this subject; and according to their 

 observations, only from seven to nine-tenths of the heat generated 

 in the organism can be referred to oxidation. Too much im- 

 portance must not, however, be attached to these results, for it 

 must be admitted that the method of investigation employed by 

 these inquirers was not entirely free from blame, while, moreover, 

 they exhibited extraordinary instability in their estimate of the 

 number of the units of heat developed from the carbon, as well as 

 from the hydrogen, during oxidation. If, however, future investi- 

 gations should enable us to become better acquainted with the 

 heat that is evolved from the combustion of the carbon and 

 hydrogen (and especially to determine it with accuracy in those 

 cases where, as in the animal organism, the elementary atoms to 

 be burned must be only gradually dissolved by the oxygen from 

 very complicated compounds), and if repeated zoo-calorimetric 

 investigations, free from the errors of the above-named physicists, 

 should lead to the desired result, that the animal heat which 

 is developed entirely corresponds to the quantity of carbon and 

 hydrogen burned in the body, then it would indeed appear most 

 wonderful that other chemical excitants of heat, which are suffi- 

 ciently obvious to every one, should be altogether excluded from 

 the animal organism. Why should the chemical union of acid 

 and base, and the many decompositions and other processes, 



* Ann. de Chim. et de Phys. 3 Ser. T. 26, p. 1-86. 

 t Ibid. 2 Ser. T. 26, p. 54-110. 



