URINE 



165 



All these phosphates are dissolved by acids, such as acetic acid, 

 without effervescence. 



They do not dissolve on heating the urine; in -fact, the amount 

 of precipitate may be increased by heating. 



A solution of ammonium carbonate (l-in-5) eats magnesium 

 phosphate away from the edges ; it has no effect on the triple phos- 

 phate. A phosphate of calcium (CaHP0 4 + 2H 2 0) may occasionally 

 be deposited in acid urine. Pus in urine is apt to be mistaken for 

 phosphates, but can be distinguished by the microscope. 



Deposit of calcium carbonate, CaCO 3 , appears but rarely as 

 whitish balls or biscuit-shaped bodies. It is commoner in the urine 

 of herbivora (see p. 154). It dissolves in acetic or hydrochloric acid, 

 with effervescence. 



The following is a summary of the chemical sediments that may 

 occur in urine : 



CHEMICAL SEDIMENTS IN URINE 



IN ACID URINE 



Uric Acid. Whetstone, dumb- 

 bell, or sheaf-like aggregations of 

 crystals deeply tinged by pigment 

 (fig. 46). 



U rates. Generally amorphous. 

 The acid urate of sodium (fig. 47) and 

 of ammonium (fig. 48) may some- 

 times occur in star-shaped clusters of 

 needles or spheroidal clumps with 

 projecting spines. Tinged brick-red. 

 Soluble on warming. 



Calcium Oxalate. Octahedra, 

 so-called envelope crystals (fig. 49). 

 Insoluble in acetic acid. 



Cystin. Hexagonal plates (fig. 

 50). Bare. 



Leucineand Tyrosine. Rare. 



Calcium Phosphate. 



CaHPO 4 + 2H,0. Rare. 



IN ALKALINE URINE 



Phospha tes. Calcium phosphate, 

 | Ca 3 (P0 4 ) 2 . Amorphous. 



Triple phosphate, 



MgNH 4 PO i + 6H,O. Coffin-lids or 

 feathery stars (figs. 45 and 51). 



Calcium hydrogen phosphate, 

 CaHP0 4 . Rosettes, spherules, or 

 dumb-bells (fig. 52). 



Magnesium phosphate, 

 Mg 3 (PO 4 ) 2 + 21^0. Long plates. 



All soluble in acetic acid without 

 effervescence. 



Calcium Carbonate, CaC0 3 . 

 Biscuit-shaped crystals. Soluble in 

 acetic acid with effervescence. 



Ammonium Urate, 

 C 5 H 2 (NH 4 ) 3 .N 4 3 . ' Thorn-apple ' 

 spherules. 



Leucineand Tyrosine. Very rare. 



