352 EXCRETION. 



gravity and acidity of the urine in cases of disease, it will not be 

 sufficient to examine any single specimen taken at random ; but all 

 the different portions discharged during the day should be collected 

 and examined together. Otherwise, we should incur the risk of 

 regarding as a permanently morbid symptom what might be 

 nothing more than a purely accidental and temporary variation. 



The chemical constitution of the urine as it is discharged from the 

 bladder, according to the analyses of Berzelius, Lehmann, Becquerel, 

 and others, is as follows : 



COMPOSITION OF THE URIXE. 



Water 938.00 



Urea 30.00 



Creatine 1.25 



Creatinine .......... 1.50 



Urate of soda -v 



" potassa [ 1.80 



" ammonia J 



Coloring matter and \ , on 



Mucus y 



Biphosphate of soda 



Phosphate of soda 



potassa 



12.45 



magnesia 

 " lime 



Chlorides of sodium and potassium 7.80 



Sulphates of soda and potassa ....... 6.90 



1000.00 



We need not repeat that the proportionate quantity of these 

 different ingredients, as given above, is not absolute, but only 

 approximative; and that they vary, from time to time, within 

 certain physiological limits, like the ingredients of all other animal 

 fluids. 



The urea, creatine, creatinine and urates have all been suffi- 

 ciently described above. The mucus and coloring matter, unlike 

 the other ingredients of the urine, belong to the class of organic 

 substances proper. They are both present, as may be seen by the 

 analysis quoted above, in a very small quantity. The coloring 

 matter, or urosacine, is in solution in a natural condition of the 

 urine, but it is apt to be entangled by any accidental deposits which 

 may be thrown down, and more particularly by those consisting of 

 the urates. These deposits, from being often strongly colored red 

 or pink by the urosacine thus thrown down with them, are known 

 under the name of " brick-dust" sediments. 



The mucus of the urine comes from the lining membrane of the 



