PART II. 



COMPARISONS OF RESPIRATORY EXCHANGE AS MEASURED BY 

 DIFFERENT TYPES OF APPARATUS. 



The following comparisons of respiration apparatus and methods 

 were made in this study: 



Bed respiration calorimeter and Benedict universal respiration apparatus 



(tension-equalizer unit) . 

 The two types of the Benedict universal respiration apparatus, i. e., 



tension-equalizer unit and spirometer unit. 

 Zuntz-Geppert apparatus and tension-equalizer unit. 

 Zuntz-Geppert apparatus and spirometer unit. 

 Tissot apparatus and tension-equalizer unit. 

 Tissot apparatus and spirometer unit. 

 Douglas respiration apparatus and spirometer unit. 

 Mouth- and nose-breathing with tension-equalizer unit. 

 Mouth- and nose-breathing with spirometer unit. 

 Mouth- and nose-breathing with Tissot apparatus. 

 Mask and nosepieces with spirometer unit. 

 Glass and pneumatic nosepieces with spirometer unit. 

 Mueller valves and Tissot spirometer with spirometer unit. 

 Mueller valves and Tissot spirometer with Tissot valves and spirometer. 

 Spirometer unit with and without additional dead space. 

 Tissot apparatus with and without automatic counterpoise on the 



spirometer bell. 



The statistics and detailed results for all of the experiments in the 

 various series are given in the following pages. Except in a few 

 instances, the experiments were made in the morning and with the 

 subject in the post-absorptive state, 1 i. e., 12 hours after the last meal. 

 The two forms of apparatus were ordinarily placed side by side, so that 

 either could be used with but little delay, thus minimizing the time 

 between the periods with the two apparatus and securing a uniform 

 environment. The subject usually lay upon a husk mattress or upon 

 an air mattress especially made for the purpose. As a rule he wore his 

 ordinary clothing and was lightly covered with blankets. His head 

 rested comfortably upon a pillow. In the bed calorimeter he lay nearly 

 always upon his side, but in the experiments with the other forms of 

 respiration apparatus he lay upon his back. In a few experiments he 

 sat up in a chair. Even in the longer calorimeter experiments he was 

 requested to keep as nearly as possible absolutely quiet, especially in 

 the later experimenting, and was also required to keep awake. 



The two apparatus were used either alternately or in series, the 

 periods following each other as rapidly as technique would permit. 

 Ordinarily the subject lay down upon the couch or entered the appara- 

 tus at least half an hour before the experiment began. In the statistics 

 of the experiments the length of this preliminary period will be given 



Benedict and Cathcart, Carnegie Inst. Wash. Pub. 187, 1913, p. 71. 



83 



