AvMlyses of Books, 



[MarcHj 



of 247*7 degrees ; so that no less than 147*7 degrees must have 

 entered the body. 



I do not^ for my own part, lay any stress upon these estimates ; 

 because I consider the whole doctrine relative to the absolute 

 heat of bodies as destitute of foundation, and because I conceive 

 Pr. Crawford's experiments to determine the specific heat of the 

 gases as too delicate to admit of precision. They are stated 

 merely to show that Dr. Crawford's theory does not depend 

 alone upon his estimate of the specific heat of arterial and 

 venous blood. It is the result of a very numerous train of 

 experiments^ investigated with much labour and ingenuity, and 

 all admirably coinciding in one point. The difference between 

 the specific heat of arterial and venous blood serves only to 

 account for the circumstance that the temperature in the lungs 

 is not higher than in other parts of the body, and to explain in 

 what manner the heat absorbed in the lungs is gradually deve- 

 loped during the circulation. 



Independent of Dr. Crawford's experiments, there are other 

 circumstances which throw considerable plausibility upon the 

 opinion that heat is evolved by respiration. Every body knows 

 that those animals that do not perspire are cold blooded, and that 

 in ourselves the temperature increases when we respire more 

 rapidly than usual, and likewise when the circulation becomes 

 accelerated o The change of oxygen gas into carbonic acid gas is 

 accompanied with an evolution of heat in all other cases with 

 which we are acquainted. This holds in combustion in a re- 

 markable degree. It holds no less remarkably during the 

 fermentation of malt liquors. Why should it not hold equally 

 in respiration ? 



These circuilistances are not sufficient to set aside Mr. Brodie's 

 experiments, which seem to have been made with great care, 

 and which are very satisfactory ; but they ought to induce us to 

 consider the subject on all sides before we embrace the conclusion 

 to which these experiments seem to lead. Living bodies do not 

 seem to be subject to the same laws as dead matter. Mr. Brodie 

 has shown that animal heat depends upon the action of the 

 brain. Dr. Currie, in a very interesting paper published in the 

 Philosophical Transactions more than 20 years ago, but to which 

 physiologists have hitherto paid no attention, has shown, by 

 experiments little less conclusive than those of Mr. Brodie, that 

 the evolution of heat is connected with the action of the sto- 

 mach. I shall take the first opportunity that occurs to reprint 

 Dr. Currie's paper in a future number of the Annals of Philoso- 

 phij, m order to contribute as far as in my power to draw the 

 attention of physiologists to a very curious subject still imperfectly 

 pnderst(!od. 



XXL On the different Structures and Situations of the 



