240 THE ATMOSPHERE, AND 



nated with the particles of the exhalations, which are de- 

 posited with them upon the surfaces of other bodies, when 

 they remain in contact, or enter into combination, with 

 them. The origin and dissemination of many maladies 

 may be traced to this source ; the germ of them is carried 

 through the air by the aqueous fluid. And for the same 

 reason it is, that intermittent fevers are endemic in those 

 situations where large quantities of vegetable matter are 

 undergoing decomposition, as upon the borders of ponds 

 and marshes ; and that the miasm, which arises from nu- 

 merous animal remains, in a state of decomposition, be- 

 comes a fruitful source of disease. It is for the same rea- 

 son also dangerous, under some circumstances, to breathe 

 the evening air ; the aqueous fluid contained in it is loaded 

 with noxious principles, which the heat of the sun, during 

 the day, had caused to ascend into the atmosphere. The 

 disagreeable odor, conveyed to us in mists, is owing to 

 the power of the aqueous fluid in transmitting the exhala- 

 tions arising from the earth. The manner in which the 

 air conveys to us the perfume of plants, and the odors 

 which it contracts from the exhalations of bodies in a state 

 of decomposition, indicates clearly its influence in produ- 

 cing maladies, and still more plainly its power of propaga- 

 ting those that are contagious." — Chemistry applied to 

 Agriculture. 



According to the best authorities, a man inhales, or takes 

 into his lungs, from six to ten pints of air at every respi- 

 ration or breath. This air comes in contact with the 

 blood in the lungs, and both the blood and the air un- 

 dergo a material change in consequence. The blood im- 

 bibes a portion of the oxygen from the air, assumes a 

 florid red hue, and acquires thereby the power of sup- 

 porting life, and is fitted to become a part of the living ani- 

 mal. The air receives, in return for the oxygen, or vital 

 air, which it gives to the blood, about an equal portion 

 of carbonic acid, which vitiates it, and renders it unfit for 

 further respiration ; or, if this vitiated or impure air is 

 again respired, the blood becomes likewise vitiated by its 

 contact with it, and all its functions become more or less 

 disordered. Atmospheric air, as we have observed, con- 



