Kotices respccltrig New Books. 277 



the secretory functions of the animal must, at this period, 

 be suspended, inconsequence of which the air in contact 

 with it underajoes no chanire ; but wlien heat is restored, 

 the blood ao;ain renews its motion, the secretory functions 

 return, and the air undergoes its accustomed chanires. Thess; 

 changes consist in the conversion ol" its oxygen gas into car- 

 bonic acid, by carbon emitted by these auiuials ihrough the 

 medium of their respiratory organs. By tlKsc means a quan- 

 tity of the specific caloric of that gas is at the instant set 

 free; and to this constant liberation of caloric by the per- 

 petual decomposition of the air, do we ascribe that supe- 

 riority of temperature above the surrounding n}edium which 

 those animals, as well as vegetables, during the continuance 

 of living action are enabled to exhibit and preserve. 



" In what manner, then, does the air breathed by the su- 

 perior animals give out its heat to support that high degree 

 of temperature above the surrounding medium, which tiiey 

 all possess? We have seen reason to conclude that the in- 

 spired air is decomposed in the bronchial cells of the lungs 

 (which contain a superficies more than ten tim.es greater 

 than that of the whole ijodv), and that all its oxygenous 

 portion, which disappears, is converted into carbo.iic acid by 

 carbon emitted from tlie exhalant surface of tiiose organs. 

 During this gradual conversion of the oxvgen gas, aquaniiey 

 of specific caloric, much creater than what is necessary to 

 maintain the elasticity of the carbonic acid that is formed, 

 is necessarily set free; and to this excess of hea , thus con- 

 stantly liberated in the iuucs by the decouiposition of the 

 air, do we look as ihc; source of that superiority of tempera- 

 ture above the surrounding medium, which man, .lad other 

 animals, under every vicissitude of clinjatCj arc enabled to 

 exhibit and maintain " 



The author proposes to pursue this iuvpiiry, provided the 

 present volume meets the approbation of the public. Tins 

 we think certain, and cannot doubt that he has long since 

 received sufficiently flatterlnq; encouragement to induce luiu 

 not to suspend his important researches. lie modestly slates 

 that he has " got rid of much error and absurdity, bu' has 

 aitaiued nothing complete;" but «' the extensive series of 

 S 3 hicts 



