208 Metabolism of Healthy Man. 



The possibilities of enormous variations in the ratio of carbon dioxide elimi- 

 nated to water vaporized can be seen in the experiments made by Schattenf roh x 

 who, working with the respiration chamber in Buhner's laboratory on a very fat 

 man, weighing 95 kilos, found in 3 experiments at a temperature of 20 C. and 

 a relative humidity of about 40 per cent, a ratio of carbon dioxide eliminated to 

 water vaporized of 100 : 316. This enormous increase in the water vaporized 

 from the skin of a fat man is a subject of considerable discussion by the author. 

 The author considers the results are doubtful and uncertain. In contrast to 

 these 3 experiments, there was a fourth made with a relative humidity of 65 

 per cent at a temperature of 20 C. where the ratio of carbon dioxide to water 

 was 100 : 105, practically a normal value. In spite of this experiment, the 

 author concludes that fat people give off about 60 per cent more water per 

 square meter of body-surface than do thin people. 



Staehelin, 2 working with the Jaquet respiration apparatus in Basel, so modi- 

 fied as to include the determination of moisture in the outcoming air-current, 

 made a series of experiments during the night when he was quietly lying asleep. 

 In some experiments after food and in another without food, both the carbon- 

 dioxide elimination and water vaporized were determined and hence the ratios 

 for carbon dioxide eliminated to water vaporized are easily computed. After 12 

 hours' fast he found 100 : 107; after mixed diet. 101 ; after fat diet, 103 ; after 

 protein diet, 99 ; and after a protein and carbohydrate diet, 93. 



Conclusions. An examination of the ratios between the carbon-dioxide elimi- 

 nated and water vaporized found in the experiments here reported and in those 

 of other investigators leads directly to the conclusions recognized early by 

 Wolpert, that relative humidity, temperature, and likewise the general physical 

 condition of the subject may all play an important role in this relationship. 

 The factor most profoundly affected is undoubtedly the water vaporized from 

 the lungs and skin. It is seriously to be questioned if any relations that have 

 bygienic or other scientific value can be found between the carbon-dioxide elimi- 

 nation and water vaporization, as this ratio is the resultant of a number of 

 variables affecting each of the two factors. 



RESPIRATORY QUOTIENT AND CALORIFIC EQUIVALENTS OF CARBON 



DIOXIDE AND OXYGEN. 



Oxygen is taken out of the air into the lungs and there carried by the blood 

 to different parts of the body where it takes part in the oxidation of body mate- 

 rial and forms carbon dioxide, which is carried by the blood to the lungs and 

 then escapes into the air. In the oxidation of this body material, the proportion 

 of oxygen to carbon dioxide will, it is evident, depend considerably upon the 

 nature of the material burned. Between the volume of the oxygen consumed 

 and the volume of the carbon dioxide eliminated, there is a definite ratio de- 

 pending upon the chemical nature of the material oxidized ; consequently, the 



1 Schattenfroh, Archiv f. Hygiene, 1900, 38, p. 108. 



2 Staehelin, Zeitschr. f. klin. Med., 1906, 66, p. 201. 



