ACIDOSIS TESTS 221 



to the level of the CO 2 . This volume is read off in the calibrated upper stem of 

 the pipette (calibrated in 0.02 c.c. divisions) and the calculations made accordingly. 

 Normal serum binds about 75% of its volume of CO 2 while in acidosis figures as 

 low as 20% may be obtained. 



For the determination of the CO 2 content of alveolar air the apparatus 

 of Fridericia is quite practical. In this the volume of CO ? in 100 c.c. 

 of alveolar air is obtained. In such methods temperature plays so 

 important a part in estimating volume that it is hardly applicable 

 except in the hands of one accustomed to gas analysis. 



We have constructed an apparatus, using a Sedgwick aerobioscope as an air 

 chamber and fitting the ends with glass stopcocks. The patient having expired, 

 to get rid of air in upper air passages, then with forced expiration fills the 200 c.c. 

 chamber of the aerobioscope, immediately afterward closing the stopcocks. We 

 then introduce 5 c.c. of N/i KOH, shaking at intervals for one-half hour to allow 

 absorption of CO 2 by the KOH. We then add a few drops of phenolphthalein as 

 indicator and titrate in the aerobioscope chamber the loss in alkalinity of the 

 KOH, using N/i HC1. (For hydrogen-ion concentration method see Appendix.) 



Besides the tests for serum acidosis of Sellards and that for carbon 

 dioxide content of alveolar air we should also determine ammonia 

 nitrogen output as well as its quotient. 



Urinary tests for acidity and acetone bodies content of the urine should also be 

 made as well as that for alkali tolerance. These tests are all very simple and can be 

 easily carried out by any well-trained laboratory worker. 



