Specific Gravity of Urine. 351 



of drinking-water consumed. If the volume of ingested water is small the 

 volume of urine may exceed it several times. When the volume of drinking- 

 water is over 1000 cc. the volume of urine is usually not far from that of the 

 water consumed. 



REACTION. 



In all of the samples of urine, whether tested by periods or for the whole 

 day, the reaction was acid. The pressure of other work prevented an accurate 

 determination of the degree of acidity. According to Brugsch (12), however, 

 the acidity, at least in the later stages of a prolonged fast, remains nearly 

 constant from day to day. 



SPECIFIC GRAVITY. 



Normal urines vary widely in their specific gravity, large volumes of urine 

 being generally accompanied by a low specific gravity and small volumes by 

 a high specific gravity. In the first three experiments here reported the specific 

 gravity was taken with a carefully calibrated urinometer with which, however, 

 it was practically impossible to make accurate record to the fifth significant 

 figure. In all subsequent experiments a Westphal balance was used. For 

 purposes of comparison it is important that the Lemperature of the urine be 

 constant when the specific gravity is taken, and hence all determinations were 

 made at 20 C. If the urine was colder than 20 it was warmed by an electric 

 heater. 



It is probably true, since the specific gravities in the experiments of earlier 

 observers are as a rule recorded only to the third decimal, that a simple hydrom- 

 eter was used. For comparing the different days of the same experiment, this 

 method is fairly satisfactory, but it obviously renders difficult any satisfactory 

 comparison between experiments not made in the same laboratory. 



In the case of Breithaupt, the specific gravity remained very constant from 

 day to day, the lowest being 1.0110 on the second and third days, and the 

 highest, 1.0135 on the fifth day. Unfortunately the records of specific gravity 

 given for Breithaupt's urine show the specific gravity not of the urine as voided 

 but of the volume of urine to which the original 24-hour amount of urine was 

 diluted before the specific gravity was taken. Hence the results are for 

 purposes of comparison of little value. 



The specific gravity of Succi's urine, in the fast at Naples, varied from 

 1.033 to 1.026, remaining for the most part very constant at about 1.028. 



In Succi's Vienna fast the specific gravity, which was 1.023 and 1.020 on 

 the first and second days, respectively, remained almost constant at 1.030 

 during the remainder of the fast. 



Brugsch (12), in studying the urine from Succi during the fast at Hamburg, 

 records the specific gravity. During the last days, 23d to 30th, the specific 

 gravity varied only from 1.023 to 1.026, remaining for 5 successive days at 



