Water Vaporized from Lungs and Skin. 145 



tion-rate there is an actual larger ventilation of the lungs, since with deep, 

 slow breathing, there may be the same volume of air carried into the lungs in 

 a given time as with rapid, shallow breathing. 



Eubner 1 reports an experiment in which a man breathed into a specially 

 designed headpiece, and the water-vapor from the lungs per hour during rest 

 was found to be 17 grams. At rest, with deep breathing, the amount was but 

 19 grams per hour, indicating that the increased depth of respiration is not 

 accompanied by a considerable increase in the total volume of expired air. It 

 is interesting to note, furthermore, that in many of the experiments made by 

 Zuntz where work was performed, although the ventilation in the lungs in- 

 creased very considerably as noted on the dial of the gas-meter, there was like- 

 wise an increase in the oxygen consumption. In the majority of cases the 

 ratio between the oxygen consumed and the total ventilation of the lungs re- 

 mained not far from that found during resting experiments. This would 

 point strongly, therefore, towards the reliability of using the oxygen intake as 

 a factor, which when multiplied by the factor 21, gives the total ventilation. 



The difficulties attending experimentation of this kind are considerable, and 

 the admirable researches of Eubner on the water-vapor output, and Zuntz on 

 the volume of respiration of the lungs, should be supplemented by researches 

 which will show more clearly and more exactly the water-vapor exhaled from 

 the lungs under different conditions of respiration. At present in these experi- 

 ments it is necessary to assume that the rate of respiration and the depth of 

 respiration did not materially vary throughout the experiment. 



The interesting studies of Willebrand ' were made with a subject without 

 clothing, and are comparable with a number of previous observations which 

 were made by Schierbeck 3 under similar conditions, for which we can hardly 

 find place in this discussion. Willebrand's conclusions are that the water elim- 

 ination through the skin during complete rest increases slowly and proportion- 

 ately to the temperature of the surrounding air, beginning at 12 C. and going 

 to a point where sensible perspiration appears. 4 



The proportions of water-vapor eliminated from the lungs and skin of fasting 

 man have been discussed on the basis of the Zuntz calculation in considerable 

 detail in a previous publication. 5 It was there pointed out that the proportions 

 between the lungs and skin did not vary materially with the same individual 

 whether he was taking food or was without food and on the average with resting 

 man 44 per cent of the water vaporized was from the lungs. 



1 Rubner, Archiv f. Hygiene, 1898, 33, p. 151. 

 -Willebrand, Skand. Archiv f. Physiol., 1902, 13, p. 337. 



3 Schierbeck, Archiv f. Hygiene, 1893, 16, p. 203. 



4 For the literature of the subject, see the article by A. J. Kalmann, Ueber die 

 Beeinflussung der Wasserdampfabgabe der Haut durch klimatische Faktoren, durch 

 Muskelarbeit und Bader, Archiv f. d. ges. Physiol., 1906, 112, p. 561. 



'Benedict, Carnegie Institution of Washington Publication No. 77, 1907, p. 437. 



