2 JO ANIMAL HEAT. 



Dr. Black, " the conversion of oxygen into carbonic acid in 

 the lungs," and hence it appears lo be difficult to reconcile 

 either of them with the results of the experiments which have 

 been related. 

 fion* 6 ob ^ ec d " ^ ma 7» perhaps, be urged, that as in these experiments the 



ed. secretions had nearly, if not entirely ceased, it is probable that 



the other changes, which take place in the capillary vessels 

 had ceased also, and that although the action of the air on the 

 blood might have been the same as under ordinary circum- 

 stances, there might not have been the same alteration in the 

 specific heat of this fluid, as it flowed from the arteries into 

 the veins. But, on this supposition, if the theory of Dr. Craw- 

 ford be admitted as correct, there must have been a gradual, 

 but enormous accumulation of latent heat in the blood, which 

 we cannot suppose to have taken place without its nature 

 having been entirely altered. If the blood undergoes the 

 usual change in the capillary system of the pulmonary, it is" 

 probable that it must undergo the usual change in the capil- 

 lary system of the greater circulation also, since these changes 

 are obviously dependent on and connected with each other. 

 The blood in the aorta and pulmonary veins was not more 

 florid, and that in the vena, cava and pulmonary artery was 

 not less daik-coloured than under ordinary circumstances. 

 We may, moreover, remark, that the most copious secretions 

 in the whole body are those of the insensible perspiration from 

 the skin, and of the watery vapour from the mouth and 

 fauces, and the effect of these must be to lower rather than to 

 raise the animal temperature Under other circumstances, also, 

 the diminution of the secretions is not observed to be attended 

 with a diminution of heat. On the contrary, in the hot fit of 

 a fever, when the scanty dark -coloured urine, dry skin, and 

 parched mouth, indicate tha scarcely any secretions are taking 

 place, the temperature of the body is raised above the natural 

 standard, to which it falls whet) the constitution returns to its 

 natural state, and the secretions are re.-tored. 

 Dr. Crawford's It has been observed, by a distinguished chemist, that " the 

 upon the Bpeci- experiments to determine the specific heat of the blood are of 

 ficheatof so very delicate a nature, that it is difficult to receive them 

 the body znd with perfect confidence"*. The experiments of Dr. Crawford, 

 be'quettS. * ThornHM* Histc-, f thefcjkl Society, p. 129. 



