MOUTH- AND NOSE-BREATHING, BENEDICT APPARATUS. 183 



The probability curves are given in figure 48. If these are examined 

 it will be seen that the uniformity of the carbon-dioxide measurement is 

 about the same for the two methods of breathing, with a variation 

 within 2 per cent; when the variation is larger than this, the uniformity 

 is greater with the subject breathing through the nosepieces. The 

 values for the oxygen consumption also show greater uniformity with 

 the nosepiece method even with a small variation, but with a variation 



TABLE 30. Variations of average results obtained with mouth-breathing from those obtained 



with nose-breathing (spirometer unit). 



ICC 



CARBON MK EUMINATCD 



SPIROMETER UNIT 

 NOSE BREATHING 



SPIROMETER UNIT 

 MOUTH BREATHING 



10 II 12 13 14 15 16 



10 II 12 13 14 15 



6789 



PER CENT OF VARIATION 



FIG. 48. Probability curves for the series of comparison experiments with nose- and mouth- 

 breathing (spirometer unit). 



The ordinates indicate the percentage of the total number of periods and the abscissae the per- 

 centage of variation from the average. 



