152 



Metabolism of Healthy Man. 



of man. It was necessary in his apparatus to inhale through the nose, and to 

 expire through the lips with a mouthpiece. The results of the various experi- 

 ments showed remarkahle uniformity. The carbon dioxide expired from the 

 lips, reduced to and 760 mm., varied from 201 c. c. to 256 c. c, the average 

 being 232 c. c. per minute. 



Using the apparatus of Scbarling, Hannover 1 made a large number of ex- 

 periments with patients, particularly those affected with lung diseases. Four 

 experiments were made on healthy individuals. The experiments usually lasted 

 an hour and were made between 10 a. m. and 1 p. m. The results, computed 

 on the basis of carbon dioxide per hour, are given in table 61. 



Table 61. Carbon-dioxide elimination of subjects in 

 experiments reported by Hannover. 



In these experiments, as in those of Scharling's, the subject was confined 

 inside of a respiration chamber and in all probability was very quiet. 



A most extended series of observations, some of them of long duration, was 

 made on himself by Edward Smith. 2 His apparatus is characterized as being 

 the first apparatus with a mouthpiece or mask in which the total carbon dioxide 

 was absorbed and weighed. In this case the air was passed through a specially 

 constructed box containing potash which absorbed all the carbon dioxide, the 

 moisture exhaled into the air being collected over sulphuric acid and the in- 

 crease in weight in the vessels beino- noted on a sensitive balance. A consider- 

 able number of experiments were made on 4 different subjects. The results are 

 expressed in English grains, and Sonden and Tigerstedt have calculated the 

 results on the gram basis and reported them in considerable detail in their 

 report. 3 The author made a large number of experiments, studying the effect 

 of different foods and stimulants upon respiration; the time of day was like- 

 wise noted and some observations were made during sleep or during drowsiness. 

 In one experiment, Smith breathed almost uninterruptedly through the mask 

 for about 18 hours, removing it only during meals. 



From the results obtained for the 18 hours while awake, the author com- 

 puted the results for periods when the subject was asleep, and concludes that 

 the carbon dioxide excreted by the 4 subjects used in his experiments would 



1 Hannover, De quantitate relativa de absoluta acidi carbonici ab homine sano et 

 aegroto exhalati, Hauniae, 1845. 



2 Smith, Philosophical Transactions, 1859, 149, p. 681. 



3 Sonden and Tigerstedt, Skand. Archiv f. Physiol, 1895, 6, p. 101. 



