10 



COMPARISONS OF RESPIRATORY EXCHANGE. 



following is a report of an extended comparative investigation of the 

 different respiration apparatus used alone or in combination. While 

 not all possible modifications have been studied, it is believed that the 

 investigation covers enough lines for the results to be applied to respira- 

 tion apparatus in general. 



EARLIER COMPARISONS OF RESPIRATION APPARATUS. 



A number of comparisons of the respiratory exchange obtained with 

 various respiration apparatus have been made by different authors. 

 These are all more or less in the nature of compilations and not direct 

 determinations of the respiratory exchange by two or more methods 

 on the same individual under identical conditions of food, body-weight, 

 and time. 



In 1897 Johansson 1 gave the results obtained on Zuntz with the 

 respiration chamber at Stockholm and the Zuntz-Geppert apparatus 

 in Berlin. The carbon-dioxide output per kilogram per hour as the 

 result of two 2-hour periods September 21, 1897, in the chamber at 

 Stockholm, was 0.304 gm., with a body-weight of 69.5 kg. On October 

 1, 1897, at Berlin, the carbon-dioxide output was 0.285 gm. per kilo- 

 gram per hour. Both values are designated by Johansson as having 

 been obtained during complete muscular rest, although the protocols 

 state that Zuntz was decidedly quieter in the experiment at Berlin 

 than at Stockholm. 



Durig, 2 in his discussion on the results obtainable with the Zuntz- 

 Geppert method, gives a compilation of the determinations of the res- 

 piratory exchange for a number of subjects with the Zuntz-Geppert 

 apparatus, the respiration chamber of Johansson, and the respiration 

 calorimeter of Wesleyan University. The average results are given 

 in table 1. 



Table 1 . — Comparative compilation made by Durig of respiratory exchange determined 



by different methods. 



Johansson, Skand. Archiv f. Physiol., 1898, 8, p. 112. 



'Durig, Denkschriften der mathematisch-naturwissenschaftlichen Klasse der kaiserlichen 

 Akademie der Wissenschaften, Vienna, 1909, 86, pp. 120-121. 



