ALIMENTATION AND THE EXPENDITURE 145 



Measurement of gaseous exchanges of a man carrying a load 

 (author's method). 



Cal. for the energy developed by the consumption of a litre of 

 oxygen at C. and 760 millimetres pressure. 



101. The oxygen method needs very detailed examination. 

 Inter-organic combustion can be maintained, according to 

 circumstances, with one of the three kinds of aliments. Take a 

 molecule of "glucose"; its formula is C 6 H 12 O 6 , and its mole- 

 cular weight 180 grammes ( 19). It burns, forming carbonic 

 acid gas and water and evolves heat. The equation of com- 

 bustion is : 



C 6 H 12 O 6 + 60 2 = 6CO 2 + 6H 2 O -f 677-20 Cal. 



180 gr. 192 gr. 

 We deduce from this equation : 



1. That 6 volumes of oxygen give 6 volumes of CO, ; as a 



CO 

 matter of fact, the carbon only has burned ; the ratio 2 = I 



in volume. This ratio . has been given the name of "respir- 

 atory quotient." If, therefore, the subject is fed on sugars, 

 his respiratory quotient would be equal to 1. 



2. That a gramme of glucose evolves - = 3-762 Calories. 



1. oU 



3. That a gramme of oxygen corresponding to 0-699 litres 

 (measured at 0C and 760m,m) ( x ) evolves: ^ Cal. = 3-527 

 Cal., i.e., 5-04 Cal. per litre of oxygen. 



192 



(*) A litre of oxygen at and 760 millimetres, weighs about T42 gr., 

 i.e., 0'699 litres per gramme. 



