KESPIRATION. 137 



It is greater in the waking than in the sleeping hours. It 

 is more when the body is in action than when at rest ; in 

 winter than in summer. It is greater when the body is well 

 nourished than when fasting. Vlerordt found that the 

 quantity discharged was fourteen per cent, greater two 

 hours after he had dined than it was on other days at the 

 same hour, when the dinner had been omitted.* 



303 Besides the carbon of the blood, which is to be car- 

 ried away through the lungs, there is water which is not 

 needed in the body, and which finds its passage through the 

 same outlet. This water goes out in the form of vapor, and 

 ordinarily is not perceptible. But every one is familiar with 

 the visible cloud of vapor that accompanies his breath in a 

 cold winter's morning. This is but the condensation of the 

 vapor that is invisible in a warm day. The same may be 

 ascertained at any time by breathing on a looking-glass, 

 when the vapor is condensed, and becomes visible in the form 

 of water. 



304. There are other matters carried off from the body 

 through the lungs by the air. Their perceptible qualities 

 differ in various men. The breath from one is sweet, from 

 another sour, from a third foul and offensive, and from a 

 fourth, it is without perceptible odor. These disagreeable 

 odors may, in some cases, proceed from decayed teeth, or 

 from disease in the mouth, the air passages, or the lungs ; 

 but more commonly they come from direct secretions in the 

 lungs of certain matters, which existed previously in the ani- 

 mal body ; as, when one has eaten onions, his breath smells 

 of garlic. The odor of wine or spirits which have been 

 taken into the stomach, is perceptible in the breath, long 

 after the mouth has been thoroughly cleansed of these mat- 

 ters. In other cases, these unpleasant odors proceed directly 

 from some foul secretion in the lungs. The habit of chew- 

 ing or smoking tobacco gives to one's breath an odor pe- 

 culiarly offensive to others who may inhale the same air. 

 In some persons, this odor is so powerful as to taint the air 

 of a whole room as soon as they enter it. 



* Lchmanu's Physiological Chemistry, Vol. II. 



