RESPIRATION OF VARIOUS GASES l6l 



tions and disagreeable odors from the body, clothing, etc. 

 It is only that the amount of CCte serves as an indication of 

 the extent of accumulation of these materials that the 

 amount of .07 per cent, is fixed as the limit beyond which it 

 ought not to be present. This percentage of COs in air free 

 from emanations, etc., is not deleterious. 



Since 1,200 cu. in. of O are consumed per hour, about 15 

 cu. ft. will be necessary for a day ; and since the 1,200 cu. in. 

 consumed represent only about one-fourth of the O inspired, 

 60 cu. ft. will be necessary ior inspiration during twenty- 

 four hours. This amount represents some 300 cu. ft. of at- 

 mospheric air which an ordinary person must have in that 

 time. 



But this estimate allows nothing for increased respiratory 

 activity, which inevitably occurs from some of the numerous 

 conditions influencing it. It is found that in prisons and 

 other institutions of confinement it is not safe to allow each 

 person less than 1,000 cu. ft. of atmospheric air. In crowded 

 houses, where this space per individual cannot be obtained, 

 it is necessary, in order to avoid unpleasant results, to change 

 the air continuously, or at frequent intervals. Natural and 

 artificial means are employed to accomplish this end. 



Respiration of Various Gases. The inhalation of pure 

 oxygen is not deleterious unless it be under higher tension 

 than in atmospheric air, when it becomes a local irritant. 

 The blood will not, however, appropriate more than the us- 

 ual amount. Nitrous oxide will sustain respiration for a 

 time, but soon produces unconsciousness and asphyxia, prob- 

 ably because it unites so firmly with the hemoglobin of the 

 corpuscles. Hydrogen may be inhaled with impunity if it 

 contain also oxygen in the atmospheric proportion. Carbon 

 monoxide is poisonous because it unites with hemoglobin to 

 the exclusion of oxygen and will not dissociate itself. Sul- 

 phuretted, phosphoretted and arseniuretted hydrogen are de- 

 structive of hemoglobin and consequently poisonous. Pure 

 carbon dioxide cannot be inhaled for any length of time, 

 ii 



