354 Influence of Inanition on Metabolism. 



urines from the experiments here reported the factor for urines from fasting 

 men may be found from these data. 



In any attempt to secure an accurate ratio between the amount of total 

 solids and the specific gravity, it is important that all specific gravities should 

 be taken at the same temperature. Each specific gravity was taken at 20 in 

 the Middletown experiments. The volume of urine was not measured but was 

 computed from the weight and the specific gravity. Hence, any errors that 

 involve the determination of specific gravity would cause an error in the 

 volume. Usually, however, it is difficult to see how any appreciable error on the 

 volume could be made. The ratio (r) existing between the total solids and 

 the specific gravity may be expressed by the following formula: 



r - I 



b X (tp. gr. 1) 



in which (g) is the total weight of solids in volume (&) of urine. 



The ratios thus computed for the different days and experiments are recorded 

 in table 193. 



The lowest average ratio is that of experiment No. 68, 2.1; the highest is 

 that of experiment No. 73, 3.4. So far as the individual days are concerned, the 

 lowest ratio is that of the first day of experiment No. 80, 2.2, and the highest, 

 the second day of experiment No. 73, 4.1. In considering the values for the 

 ratios, it must be borne in mind that in experiments Nos. 59 and 68, the total 

 solids for individual days were apportioned by calculation. The average ratio 

 for all of the experiments is somewhat higher than that commonly assumed for 

 normal urines. 



In experiments with the same individual, there are also marked differences. 

 The ratio for experiment No. 69 is higher than that for experiment No. 68, 

 which was made with the same individual some 8 months earlier. In the series 

 of experiments with S. A. B., the average ratio for the first three is fairly 

 constant, 3.0, 3.4, and 3.3. In the last experiment (No. 77), the average 

 falls to 2.5. 



In the longer fasts (experiments Nos. 69, 71, 73, 75, and 77) the average 

 ratio is 2.9. Obviously during a fast, the relative amounts of organic and 

 inorganic matter in the urine may vary considerably from those obtained 

 when food is eaten. The amount of sodium chloride taken with the food, for 

 example, may affect considerably the specific gravity. As has been pointed out, 

 the specific gravity increases much more in proportion with an increase of 

 sodium chloride than with urea. The larger the proportion of organic matter 

 which consists in large part of urea, the lower the specific gravity with refer- 

 ence to a given weight of total solids and hence the higher the ratio. Thus a 

 knowledge of the relative amounts of organic and inorganic matter in the total 

 solids is essential to an understanding of the variations in the relationship 

 between specific gravity and total solids during fasting. 



