140 Metabolism of Healthy Max. 



The large surface of the body and the hygroscopic nature of the clothing 

 about the person make it extremely difficult to state absolutely what is the 

 weight of water-vapor leaving the body itself. It is impossible from the water 

 determinations to distinguish between 1 gram of water vaporized from the 

 lungs or skin of a man and 1 gram of water vaporized from the clothing. The 

 problem of determining exactly the water vaporized from the lungs and skin 

 of the man is extremely complicated. It is necessary to take into consideration 

 the moisture-content of the clothes, the muscular activity of the individual, 

 the relative humidity * of the air, the temperature of the air and of the body, 

 and probably other as yet unknown factors. Investigations of this nature are 

 highly desirable, and until such an investigation is carried out we must content 

 ourselves with the results obtained in the experiments thus far made, which 

 are admittedly somewhat crude. 



In the experiments, the subject sits in an arm-chair or lies on a cot-bed 

 inside the respiration chamber; he is covered with clothing of a more or less 

 hygroscopic nature and makes relatively slight muscular movement. While, as 

 a rule, sudden and marked changes in the relative humidity are not common, 

 the humidity may change considerably in a short time. The results deal only 

 with the water vaporized from the lungs and skin, or the water-vapor that 

 left the respiration chamber and was carried by means of the air-current to 

 the sulphuric-acid vessels, due corrections being made for the variations in 

 water-vapor present in the chamber at the beginning and end of the several 

 periods. No water in the urine, drink, feces, or food is taken into consideration. 



water vaporized during waking hours. 



The water-vapor eliminated during the waking hours by different subjects 

 has been collected in table 54, in which the subjects are placed in the order 

 of their body-weights. For purposes of comparison and for use in the general 

 discussion of many of these results, an abstract of the body-measurements is 

 given in that the body-weight and height of each subject are shown in the 

 table. The water-vapor eliminated per hour, the amount per kilo per hour, 

 and the amount per square meter of body surface per hour, are likewise shown 

 for each subject, these figures being the average of several experiments with 

 each man. The total amount eliminated per hour varies considerably among 

 the different subjects, the highest being 52.7 grams with W. E. D., and the 

 lowest 25.7 grams with H. E. D. The average of all experiments is 38.7 grams 

 per hour. The temperature of the chamber was 19 to 21 C. The relative 

 humidity varied from 30 to 55 per cent, but in the larger number of experiments 

 it was about 50 per cent, 



1 Rubner and his associates have taken up the problem from the hygienic stand- 

 point, and their results are of great general interest, though open to criticism. (See 

 Benedict, Carnegie Institution of Washington Publication No. 77, 1907, p. 433.) 



