OXYGEN CONSUMED AND CARBON DIOXIDE EXHALED 153 



(d) Gain of Water. This water is in the form of vapor. It is 

 natural that the air should absorb water from the moist surfaces 

 with which it is in contact. The capillary network with which 

 it is in close relation supplies moisture to the mucous membrane 

 not only of the alveoli but of the entire respiratory tract. One 

 or two pounds of water are eliminated thus daily. 



(e) Gain of Ammonia. Ammonia is exhaled in small quan- 

 tity by the lungs. It is insignificant except in cases of suppressed 

 kidney action. 



(/) Gain of Organic Matter. The quantity of organic matter 

 exhaled by the lungs is inconsequential (unless ventilation be 

 bad), but such exhalation does occur to a small extent. It gives 

 the odor to the breath. 



(g) Gain of Nitrogen. The exhalation of this gas by the 

 lungs is of no respiratory importance. The amount is said to 

 be ito sV * ne amoun t of oxygen consumed. An occasional 

 loss of nitrogen has been observed. 



(h) Decrease of (Actual} Volume. When the external tem- 

 perature is below about 90 F. the volume of expired air is a 

 little greater than that of the inspired air, because of the increase 

 of temperature it undergoes in passing through the lungs. But 

 the actual volume of the expired air, when reduced to the same 

 temperature as the inspired, is found to be always a little less 

 than that of the latter. It is estimated that from ^Wo f tne 

 total volume of the inspired air is thus lost in respiration. 



Besides the substances mentioned as being exhaled from the 

 lungs, it is well known that odorous emanations proceed from 

 them after garlic, onions, turpentine, alcohol, certain drugs, etc., 

 have been taken into the stomach. 



Relation Between Oxygen Consumed and Carbon Dioxide 

 Exhaled. A given volume of O will combine with carbon to 

 form the same volume of CO 2 ; or the amount of O in a given 

 volume of CO 2 is equivalent to that volume when set free from 

 the carbon. A cubic foot of will unite with carbon to form 



