158 HEALTHY URINE. 



passed, it will change in reaction. According to tempera- 

 ture and circumstances, often in 24 hours it undergoes 

 the alkaline fermentation by the micrococcus urea, which 

 breaks up urea, yielding carbonate of ammonia in the 

 solution. This change may occur in the bladder when a 

 dirty catheter is employed to draw off urine. Such urine 

 becomes turbid, smells of ammonia, a surface scum forms, 

 and a heavy white pp of phosphates of Ca and Mg 

 deposits. 



Specific Gravity. 1020 average. Taken by means of a 

 urinometer. This is a small hydrometer graduated for 

 the purpose from to 50, the last figures of the S.G. 

 expressed in four figures. 



Inorganic Constituents. 



"Water. Varies according to activity of skin ; the S.G. 

 indicates its proportion to total solids. A rough approxi- 

 mate estimation of the total solids for urines of ordinary 

 densities can be made by the Christison-Tyson formula. The 

 quantity of solids per 1,000 parts urine is obtained by multi 

 plying the last two figures of the S.G. expressed in four 

 figures of urine of 24 hours by 2 -33. Not applicable to 

 urines which contain sugar or albumin. 



Chlorides. Chiefly of Na, are soluble, do not deposit. 

 In 24 hours, 10 15 g - (Urea to chlorides, 2 : 1.) 



Test. Take one-quarter tube of urine ; add 2 drops HNO 3 

 and half volume of AgN0 3 4 p - c - solution = white pp ; 

 shake thoroughly, and let stand. Deposit normally 

 about one-quarter volume of urine ; the HNO 3 keeps 

 phosphates in solution. 

 Increased by diet ; diminished in fevers. Not clinically 



important. 



