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 Crawrorp inferred from 
his experiments, that the specific heat of oxygen was as 
4.7490, carbonic acid 1.0454, azote 0.7936, atmospheric 
ar 1.7900. The more recent and accurate experiments 
of MM. Detarocue and Brrarp, 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 Buacx, 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 blocd 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 front those of Dr Joun 
Davy already quoted *. 
* Page 353. 
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