234 COMPARISONS OF RESPIRATORY EXCHANGE. 



tambours, and kymographs, and similar matters. The manipulation 

 of the apparatus requires the utmost concentration, but it can not be 

 said to be really difficult and any investigator familiar with laboratory 

 methods in physiology and chemistry should be able to carry out the 

 routine without additional training. 



Like any good physiological apparatus, this respiration apparatus 

 necessitates a certain amount of constant care. If the apparatus is 

 kept in good condition, our experience has been that after a month or 

 two of disuse it can be employed for experiments with but little pre- 

 liminary repair. Certain portions of the rubber connections deteri- 

 orate and must occasionally be renewed; if a superficial examination 

 does not show such defects, a test for leaks immediately reveals any 

 weakness of this character. The two three-way valves 1 which provide 

 for using either one of duplicate absorbing systems are sometimes found 

 to leak and to require re-grinding. The other parts of the apparatus 

 rarely need attention, provided they have been well constructed. The 

 filling of the soda-lime bottles and sulphuric-acid containers does not 

 need particular training. The soda-lime may be made, 2 as has been the 

 custom in this laboratory, or may be purchased ready for use in con- 

 tainers of suitable size. 



In conclusion, it may be stated that the chief advantages of the 

 Benedict respiration apparatus are the rapidity with which experi- 

 ments of short duration may be carried out and the exact graphic 

 record of the respiration which may be obtained with the spirometer 

 type. The disadvantages are the difficulty in obtaining absolute 

 freedom from leaks in the connections of the apparatus to the subject 

 and the possibilities of unreliable determinations of the oxygen con- 

 sumption due to irregularities in the volume of the lungs. With the 

 majority of individuals, the breathing is normal and the results of the 

 measurements of the respiratory exchange are accurate. 



ZUNTZ-GEPPERT APPARATUS. 



The Zuntz-Geppert apparatus is, in all probability, the most used 

 respiration apparatus in existence. It has been very extensively 

 employed in Europe, where an enormous amount of work has been done 

 with it, and to a slight extent in American laboratories. 



The apparatus has been criticized by Magnus-Levy 3 in his descrip- 

 tion of it, also by Durig in his reports on the Monte Rosa expedition 4 

 and on the effect of oxygen-rich atmospheres on the respiratory 

 exchange. 5 In all of these the discussion is mainly on the question of 

 the gas analysis and on the probability of error and the limits of error 



J See p. 41. 



2 Benedict and Talbot, Carnegie Inst. Wash. Pub. 201, 1914, p. 40; and Benedict, Deutsch. 

 Archiv f. klin. Med., 1912, 107, p. 166. 



3 Magnus-Levy, Archiv f. d. ges. Physiol., 1894, 55, p. 1. 



4 Durig, Denkschriften der mathematisch-naturwissenschaftlichen Klasse der kaiserlichen 

 Akademie der Wissenschaften, Vienna, 1909, 86, p. 116. 



6 Durig, Archiv f. Anatomie und Physiologie, Physiologische Abteilung, 1903, p. 209. 



