566 



THE URINE 



[CII. XXXVII. 



Carbonates. Carbonates and bicarbonates of sodium, calcium, 

 magnesium, and ammonium are only present in alkaline urine. 

 They arise from the carbonates of the food, or from vegetable acids 

 (malic, tartaric, etc.) in the food. They are, therefore, found in the 

 urine of herbivora and vegetarians, whose urine is thus rendered 

 alkaline. Urine containing carbonates becomes, like saliva, cloudy 

 on standing, the precipitate consisting of calcium carbonate, and 

 also phosphates. 



Phosphates. Two classes of phosphates occur in normal urine : 



(1) Alkaline phosphates that is, phosphates of sodium (abundant) 

 and potassium (scanty). 



(2) Earthy phosphates that is, phosphates of calcium (abundant) 

 and magnesium (scanty). 



The composition of the phosphates in urine is liable to variation. 



FIG. 481. Urinary sediment of triple phos- 

 phates (large prismatic crystals) and 

 urate of ammonium, from urine which 

 had undergone alkaline fermentation. 



FIG. 432. Mucus deposited from urine. 



In acid urine the acidity is due to the acid salts. These are 

 chiefly : 



Sodium dihydrogen phosphate, NaH 2 P0 4 , and calcium dihydrogen 

 phosphate, Ca(H 2 P0 4 ) 2 . 



In neutral urine, in addition, disodium hydrogen phosphate 

 (N"a. 2 HP0 4 ), calcium hydrogen phosphate, CaHP0 4 , and magnesium 

 hydrogen phosphate, MgHP0 4 , are found. In alkaline urine there 

 may be instead of, or in addition to, the above, the normal phosphates 

 of sodium, calcium, and magnesium [Na 3 P0 4 , Ca 3 (P0 4 ) 2 , Mg 3 (PO d ) 2 ]. 



The earthy phosphates are precipitated by rendering the urine 

 alkaline by ammonia. In decomposing urine, ammonia is formed 

 from the urea: this also precipitates the earthy phosphates. The 

 phosphates most frequently found in the white creamy precipitate 

 which occurs in decomposing urine are : 



(1) Triple phosphate or ammonio - magnesium phosphate 



