EXPERIMENT WITH MAN. 



185 



When carbohydrates are burned in the body, the volume of oxygen 

 consumed is equal to the volume of carbon dioxide given off, since 

 the hydrogen and oxygen in the carbohydrate molecule are in the 

 same proportions as in water, and in the conversion of carbon to 

 carbon dioxide the volume of carbon dioxide is invariably the same as 

 the volume of oxygen required. In the case of the proteids, where 

 not only carbon is oxidized, but also some hydrogen, it is found that 

 the respiratory quotient is generally not far from 0.809, while in the 

 case of fats, where the amount of hydrogen oxidized is quite consider- 

 able, the respiratory quotient may fall as low as 0.711. It has been 

 found as a result of experimenting with other types of respiration 

 apparatus, especially those of Zuntz and Chauveau (see p. 3), that 

 the respiratory quotient on an ordinary mixed diet is not far from 0.9. 

 From an inspection of column (^) of Table 10 of experiment 70 given 

 herewith, it will be seen that the large proportion of fat in the diet re- 

 sulted in a marked lowering of the respiratory quotient. 



SUMMARY OP CALORIMETRIC MEASUREMENTS. 



The records of the heat measurements by means of the respiration 

 calorimeter are summarized in Table n. 



n. Summary of Calorimetric Measurements, Metabolism Experiment 



No. 70. 



The major part of the heat generated within the apparatus is absorbed 

 and carried away by a current of cold water through the heat- absorbers. 

 The quantity of heat thus brought out is determined from measurement 



