THE URINE. 387 



during the night between 2-4 o'clock; the maximum, in the first 

 hours after awakening and from 1-2 hours after a meal. 



The quantity of solids secreted in the course of 24 hours is 

 rather constant even though the quantity of urine may vary, and 

 it is more constant when the manner of living is regular. There- 

 fore the percentage of solids in the urine is naturally in an inverse 

 proportion to the quantity of urine. The average quantity of 

 solids per 24 hours is calculated as 60 grins. The quantity may be 

 calculated with approximate accuracy by means of the specific 

 gravity, if the second and third decimals of the specific gravity be 

 multiplied by HASER'S coefficient 2.33. The product gives the 

 amount of solids in 1000 c.c. of urine, and if the quantity of 

 urine eliminated in the 24 hours be measured, the quantity of 

 solids in the 24 hours may be easily calculated. For example, 

 1050 c.c. of urine of a sp. gr. 1.021 was eliminated in the 24 hours; 

 therefore the quantity of solids eliminated is 21 X 2.33 = 48.9, 



and - ' = 51.35 grms. The urine in this case contained 



48.9 p. m. solids and 51.35 grms. in the daily secretion. 



Those bodies which, under physiological conditions, affect the 

 density of the urine are common salt and urea. The specific gravity 

 of the first is 2.15 and the last only 1.32, so it is easy to understand, 

 when the relative proportion of these two bodies essentially de- 

 viates from the normal, why the above calculation from the specific 

 gravity is not exact. The same is the case when a urine poor in 

 a normal constituent contains large amounts of foreign bodies, such 

 as albumin or sugar. 



As above stated, the percentage of solids in the urine generally 

 decreases with a greater elimination, and an abundant secretion 

 (polyuria) has therefore, as a rule, a lower specific gravity. An 

 important exception to this rule is observed in urine containing 

 sugar (diabetes mellitus), in which there is a very abundant secre- 

 tion of a very high specific gravity due to the sugar. In cases 

 where very little urine is secreted (oligurid), as when the perspira- 

 tion is profuse, in diarrhoea, and in fevers, the specific gravity is as 

 a rule high, the percentage of solids high, and the color dark. 

 Sometimes, as, for example, in certain cases of albuminuria, the 



