114 OF ANIMAL HEAT. 



NOTE. 



No phenomenon in living- bodies is more remarkable than their 

 peculiar temperature, and no one was of more difficult explana- 

 tion before the progress of modern chemistry. 



If two different bodies are placed in a temperature higher or 

 lower than their own for a certain length of time, they will, at 

 the end of the period, be found not of the same, but of different, 

 temperatures. That which has the higher temperature, is said 

 to have a smaller capacity for caloric ; that which has the lower, 

 a greater capacity. To raise the former to a given temperature, 

 therefore, requires less heat than to raise the latter to the same 

 degree. 



The temperature of solids is more easily affected by a given 

 quantity of heat, than that of fluids, and the temperature of fluids 

 than that of aeriform bodies : or, in other words, solids have a 

 smaller capacity for caloric, than fluids, and fluids than aeriform 

 bodies. If, therefore, a solid becomes fluid, or a fluid aeri- 

 form, it absorbs a great quantity of heat, though its temperature 

 remain precisely the same. And the converse holds equally 

 good, if an aeriform substance becomes liquid, or a liquid solid, 

 the heat which it before contained is now (from its diminished 

 capacity) much more than sufficient for the temperature which 

 before existed, and the temperature of the body accordingly rises. 



In respiration, the dark blood of the pulmonary artery parts 

 with a portion of its carbon and acquires a florid hue. This car- 

 bon unites with the oxygen of the inspired air, and forms carbonic 

 acid that is expired with the other constituent of the atmos- 

 phere, nitrogen or azote, which appears to have experienced 

 no change from inspiration. 



Dr. Crawford rendered it probable, by his experiments, that 

 the arterial blood has a larger capacity for caloric than the 

 venous, and common air than carbonic acid gas. When, there- 

 fore, the carbon of the venous blood unites with the oxygen of 



