18 



Metabolism of Healthy Man. 



to become dryer as the experiment progressed. The total amounts of water 

 vaporized likewise tend to fall off somewhat. Since the volume of air inside 

 the chamber is not far from 4900 liters, and at a temperature of 20 this 

 would, when saturated, contain 84 grams of water, it would seem that the 

 humidity was not far from 45 per cent. As this was one of the earliest experi- 

 ments made with this apparatus in its modified form, it is extremely difficult 

 to determine with the greatest accuracy the source of water vaporized inside 

 the chamber, for it may have come partly from the lungs of the subject, partly 

 from the skin, and partly from the bed and furniture. The subsequent develop- 

 ment of technique has made it possible in the majority of experiments to weigh 

 all the material in the chamber of a hygroscopic nature and thus apportion to 

 a certain degree the amount of water vaporized. 



Elimination of Carbon Dioxide. 

 The data regarding the carbon-dioxide elimination are summarized in table 

 7. As is usual in experiments of this type the amount of carbon-dioxide 

 residual inside the chamber increased somewhat during the day and fell off 

 noticeably during the night. 



Table 7. Record of carbon dioxide Metabolism experiment No. 101. 



A simple calculation from the total volume of air in the chamber and the 

 residuals as determined shows that at no time was carbon dioxide present in 

 the chamber in amounts greater than found normally with this apparatus. As 

 can readily be seen, the amounts of carbon dioxide given off fluctuated widely, 

 the smallest amount being from 7 p. m. to 1 a. m., 114.7 grams, and the largest 

 amount from 1 p. m. to 7 p. m., 197.4 grams. From the records of movements 

 made by the subject, it is difficult to understand why the carbon-dioxide pro- 

 duction was so low between 7 p. m. and 1 a. m. 



Measurements of Oxygen Consumed and Heat Eliminated. 

 Unfortunately, as the experiment with this subject was one of the first made 

 with the apparatus so modified as to include the determination of oxygen, a 



