PECULIAR SECRETIONS. 387 



is far from sufficient to supply the quantity which is con- 

 stantly abstracted. But the hypothesis has fallen, by at- 

 tacks in another direction. Dr CRAWFORD inferred from 

 his experiments, that the specific heat of oxygen was as 

 4.7490, carbonic acid 1.0454, azote 0.7936, atmospheric 

 air 1.7900. The more recent and accurate experiments 

 of MM. DELAROCHE and BERARD, however, have esta- 

 blished the relative specific caloric of the same gases as fol- 

 lows: Oxygen 0.2361, carbonic acid 0.2210, azote 0.2754, 

 atmospheric air 0.2669. It follows from these experiments, 

 therefore, that the quantity of heat given out by oxygen 

 during its conversion into carbonic acid gas, would be in- 

 sufficient to heat the residual air that is expelled in breath- 

 ing to its ordinary elevation, and consequently could con- 

 tribute nothing towards sustaining the high temperature of 

 the body. 



The objection that had been brought against the hypo- 

 thesis of BLACK, that the lungs were not hotter than the 

 rest of the body, was attempted to be obviated by Dr CRAW- 

 FORD, who assumed, from his experiments, that the specific 

 caloric of arterial blood was 1.0300, and that of venous 

 blood only 0.8928, and inferred, that, during the conversion 

 of the former into the latter, in the course of circulation, a 

 quantity of heat must be set free ; and as this conversion 

 takes place in every part of the body, heat must consequent- 

 ly be every where disengaged. But the basis of this hypo- 

 thesis has not been demonstrated to be true. It is next to 

 impossible, by the methods at present known, to deter- 

 mine with any degree of accuracy the relative specific heat 

 of arterial and venous blood ; and the conclusions of CRAW- 

 FORD on the subject, differ widely from those of Dr JOHN 

 DAVY already quoted *. 



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