HEAT IN BREATHING. 



then the air is of the proper quality ; whereas, if 

 the nose of the bellows slope downward, the 

 " burnt air" the nitrogen, and the products of 

 the fire, are blown against the fire and tend to 

 weaken it. 



The heat produced in breathing does not ap- 

 proach nearly to that of flame or combustion, but 

 still it is considerable, though it is not easy to 

 distinguish between it and the heat produced by 

 circulation. There is no reason to doubt that heat 

 might be produced by resistance to circulation, and 

 to that of breathing, among other circulations, suffi- 

 cient to kindle and consume the body; for though all 

 the recorded instances of spontaneous or inward 

 combustion are not probably true, yet so many of 

 them are mentioned that they must have at least 

 some foundation. We know that, when either the 

 breathing or the pulse of the blood is quickened, 

 either by exertion or by disease, the heat in- 

 creases in proportion ; so that while the tempera- 

 ture of health varies from about ninety-five to one 

 hundred degrees, a diseased heat may be as great 

 as one hundred and thirty or one hundred and 

 forty degrees. So also, when the breathing or 

 the circulation is very languid, the temperature 

 sinks ; and in those faintings, during which hardly 

 any pulse or breathing is perceptible, the body 

 becomes exceeding cold. 



Now, as the temperature of health is very con- 

 siderably above the average of that of the air in 

 temperate countries, and indeed above the average 

 of almost any country, it follows that the expired 

 breath, which, as has been said, is loaded with 

 the superfluous moisture of the body, must have a 

 tendency to produce dew upon the colder air 



