238 COMPARISONS OF RESPIRATORY EXCHANGE. 



ratus, which has been adopted in this laboratory for gas analyses, 

 phosphorus has been employed for the absorption of oxygen, and in one 

 portable Haldane gas-analysis apparatus it was used for over 6 months 

 without replacement. In its use, however, we take special care that, 

 even after the readings are constant, the gas remains over the phos- 

 phorus for a sufficient length of time to insure complete absorption. 



If the possibilities of the loss of carbon dioxide in the collection of the 

 gas over water and of an incomplete absorption of oxygen by phos- 

 phorus are taken into consideration, it will be seen that these may be 

 the apparent causes of the low respiratory quotients which are occa- 

 sionally obtained with the Zuntz-Geppert gas-analysis apparatus. It 

 is somewhat difficult, however, to understand why such quotients occur 

 more frequently in fever than with normal people. 



Hoppe-Seyler 1 states that in spite of every attempt to have the 

 valves, meter, and tubing free from resistance, breathing through the 

 Zuntz-Geppert apparatus is not free breathing and that long-continued 

 experiments can not be carried out with it. Katzenstein 2 says that in 

 spite of all care taken, the breathing through a mouthpiece and a meter 

 must involve work and therefore a greater metabolism will result. The 

 experiments carried out here, however, indicate that the respiration 

 with the Zuntz-Geppert method is, on the whole, normal when the 

 subjects have become accustomed to it. Even subjects who stated 

 that they expected it to be hard to breathe through the valves have, 

 after a few moments of breathing, found no great difficulty. After 

 the respiration has become uniform it is apparently perfectly normal. 

 The control upon the uniformity of the breathing can be obtained 

 directly from readings of the meter, and if these are made every minute 

 the results show whether or not there is a regularity in the ventilation 

 of the lungs in the individual minutes. This is one of the advantages 

 of the Zuntz-Geppert method and the readings thus obtained may be 

 depended upon. The practice of reporting values to the single cubic 

 centimeter or fraction thereof is not warranted by the general percent- 

 age accuracy of the apparatus, when the factors of the calibration, 

 temperature, pressure, and the personal equation in reading the results 

 are taken into consideration. 



The manipulation of the Zuntz-Geppert apparatus is in part simple 

 and in part somewhat complicated. Reading the individual ventila- 

 tion figures requires constant attention. Furthermore, the adjustment 

 of the valves is somewhat difficult, for in order to insure the most satis- 

 factory results with this apparatus, it is necessary that the valves be 

 so adjusted that resistance will be at a minimum and the valves will 

 also close properly when there is suction or pressure. We have used 

 both fish membrane and thin rubber membrane for the valves, but do 



^oppe-Seyler, Zeitschr. f. physiol. Chemie, 1894, 19, p. 578. 

 'Katzenstein, Archiv f. d. ges. Physiol., 1891, 49, p. 380. 



