CALORIFIC VALUE OF OXYGEN. 833 



constructed a table, an abstract of which we give below, taken from the 



\VOrk Of MAGNUS-LEVY. 1 



R. Q Calories value Division in per cent. 



per 1 liter 0. Carbohydrate. Fat. 



1.000 5.047 100 



0.950 4.986 83 17 



0.900 4.924 66 34 



0.850 4.863 49 51 



0.800 4.801 32 68 



0.750 4.740 15 85 



0.707 4.686 100 



As the calorific oxygen values in the combustion of protein, fat 

 and carbohydrate show no great differences among themselves, in those 

 cases where, as in starvation, the part taken by the proteins in the total 

 metabolism is relatively small, one can calculate the total energy exchange, 

 without any striking error, from the respiratory quotient and the oxygen 

 used. This is especially important in experiments of short duration 

 where the protein metabolism cannot be directly determined, but is 

 calculated from the nitrogen elimination occurring during a longer time. 

 The method of ZUNTZ and GEPPERT, mentioned on page 820, has shown 

 itself especially useful in the study of the material and force exchange 

 in these experiments of short duration, while the respiration apparatus 

 constructed on PETTENKOFER'S or REGNAULT-REISET principle are only 

 useful in experiments over a longer period. 



KAUFMANN 2 incloses the individual to be experimented upon in a capacious 

 sheet-iron room, which serves both as a respiration-chamber and a calorimeter, 

 and which permits the estimation of the nitrogen of the urine and the carbon 

 dioxide expired, as well as the inspired oxygen and the quantity of heat produced. 

 If we start from the theoretically calculated formulas for the various possible 

 transformations of the proteins, fats, and carbohydrates in the body, it is clear 

 that other values must be obtained for the heat, carbon dioxide, oxygen, and 

 nitrogen of the urine, when one, for example, admits of a complete combustion 

 of proteins to urea, carbon dioxide, and water, or of a partial splitting off of fat. 

 Another relation between heat, carbon dioxide, and oxygen is also to be 

 expected when the fat is completely burnt or when it is decomposed into sugar, 

 carbon dioxide, and water. In this way, by a comparison of the values found in 

 special cases with the figures calculated for the various transformations, KAUF- 

 MANN attempts to explain the various decomposition processes in the body under 

 different nutritive conditions. 



As will be shown, the fats and carbohydrates may decrease the metab- 

 olism of proteins in the body, while, on the other hand, the quantity 

 of proteins in the body or in the food acts on the metabolism of fat in 

 the body. In physiological combustion the various foods may replace 

 one another to a certain extent, and it is therefore important to know the 

 ratio of replacement. The investigations made by RUBNER have taught 



1 A. Magnus-Levy in v. Noorden's Handb. d. Pathol. des Stoffwechsels, Bd. 1. (1906). 



2 Arch. d. Physiologie (5), 8. 



