PART I. 



INTRODUCTION. 



The development of apparatus for measuring the respiratory ex- 

 change of man has proceeded along two lines. In one type of apparatus 

 the subject is completely inclosed in a chamber; in the other, the sub- 

 ject is attached to the respiration apparatus by means of some breath- 

 ing appliance. The chamber type includes the respiration apparatus of 

 Pettenkofer and Voit, 1 Sonden and Tigerstedt, 2 Jaquet, 3 and Grafe, 4 

 the Atwater-Benedict respiration calorimeter, 5 and the respiration 

 calorimeters of the Nutrition Laboratory. 6 This type of apparatus 

 is generally used for periods of not less than an hour and may be either 

 a closed or open circuit. The apparatus without chambers are used 

 for periods of about 15 minutes and may also be either closed or open 

 circuit. In the latter case, the inspired and expired air are separated 

 by valves. A mouthpiece, nosepiece, or mask is used for the breathing 

 appliance. The open-circuit apparatus are represented by the appa- 

 ratus of Speck, 7 Zuntz-Geppert, 8 Tissot, 9 and Douglas. 10 The closed- 

 circuit apparatus include the two types of the Benedict apparatus, 11 

 Holly's 12 modified Benedict apparatus, and that of Krogh. 13 



When the large amount of work on respiratory exchange carried out 

 with these apparatus is considered, it will be seen that the importance 

 of knowing whether the results obtained are reliable and physiologi- 

 cally comparable can hardly be overestimated. Recognizing the need 

 of a comparative investigation into the reliability of the principal 

 respiration apparatus in use to-day, the Director of the Nutrition Labor- 

 atory, in a trip to Europe in 1907, secured various apparatus for measur- 

 ing the respiratory exchange, including particularly the Zuntz-Geppert 

 and the Tissot respiration apparatus, with a view to comparing them 

 with apparatus already being developed in this laboratory. Subse- 

 quently he arranged on two occasions for the writer to visit the labora- 

 tories in Berlin and Paris, where these methods were developed, and thus 

 to become personally acquainted with the technique involved. The 



'Pettenkofer and Voit, Ann. d. Chemie u. Pharm., II Supp. Bd., 1882, p. 52. 



2 Sonden and Tigerstedt, Skand. Archiv f. Physiol., 1895, 6, p. 1. 



3 Jaquet, Verhandl. d. Naturf. Gesellsch. in Basel, 1903, 15, p. 252. 



Kjlrafe, Zeitschr. f. physiol. Chemie, 65, 1910, p. 1. 



6 Atwater and Benedict, Carnegie Inst. Wash. Pub. 42, 1905. 



'Benedict and Carpenter, Carnegie Inst. Wash. Pub. 123, 1910. 



7 Speck, Physiologic des menschlichen Athmens nach eigenen Untersuchungen, Leipsic, 1892. 



8 Magnus-Levy, Arcbiv f. d. ges. Physiol., 1894, 55, p. 1. 



9 Tissot, Journ. de physiol. et de pathol. gen., 1904, 6, p. 688. 



10 Douglas, Journ. Physiol., 1911, 42, Proc. Physiol. Soc. p. xvii. 



"Benedict, Am. Journ. Physiol., 1909, 24, p. 345; Deutsch. Archiv f. klin. Med., 1912, 107, p. 156. 



12 Rolly and Rosiewicz, Deutsch. Archiv f. klin. Med., 1911, 103, p. 58. 



13 Krogh, Skand. Archiv f. Physiol., 1913, 30, p. 375. 



