128 



ESSENTIALS OF CHEMICAL PHYSIOLOGY 



alkaline urine will become cloudy when boiled : this may be due to 

 albumin or to phosphates. It is very important to distinguish be- 

 tween these two, as aJbuminuria is a serious condition. They may 

 be distinguished by the use of acetic acid, which dissolves phosphates 

 but not albumin. 



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 (CaHP04+2H20) 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 calciuin carbonate, CaCOa, appears but rarely as 

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

 urine of herbivora (see p. 116). 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 UKINE 



In Acid Urine 



Uric Acid. — Whetstone, dumb- 

 bell, or sheaf-like aggregations of 

 crystals deeply tinged by pigment 

 (fig. 43). 



Urates. — 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 cliunps 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. 

 53). Rare. 



Leucine and Tyrosine. — Eare. 



Calcium Phosphate. 



CaHPO^ -1- 2H,0.— Hare. 



In Alkaline Urine 



Phosphates. — Calcium phosphate, 

 Ca3(P04)2. Amorphous. 



Triple phosphate, 

 MgNH.PO^ + 6H2O. Coffin-lids or 

 feathery stars (figs. 42 and 51). 



Calcium hydrogen phosphate, 

 CaHPOj. Rosettes, spherules, or 

 dumb-bells (fig. 52). 



Magnesium phosphate, 

 Mg3(P0J., -^ 22H2O. Long plates. 



All soluble in acetic acid without 

 eflFervescence. 



Calcium Carbonate, CaCOg. — 

 Biscuit-shaped crystals. Soluble in 

 acetic acid with effervescence. 



Ammonium Urate, 

 C5H,(NH,)2.N,03. — ' Thorn-apple ' 

 spherules. 



Leucine andTyrosine. — Very rare. 



