THE MICROSCOPE IN DIAGNOSIS. 313 



defective assimilation, congestion of the kidney, or chronic 

 disease of the respiratory organs. 



Urates or lithates are salts of uric acid combined with 

 soda, potash, or ammonia, the exact composition being 

 difficult to determine. Such sediments are very common. 

 They are generally amorphous, but sometimes crystalline 

 (Kate XXVI, Fig. 245). The urate of soda presents the 

 form of globules with projecting spiculae. The color is 

 various, from a light pink to brickdust color. It is de- 

 posited in all concentrated urine, and is often a "critical 

 discharge " in fevers, etc. It is found in gouty concretions, 

 and dissolves with heat and acids. 



Phosphates appear in two forms, crystalline and amor- 

 phous. The crystalline are the crystallized phosphate of 

 lime, and the ammonio-magnesian (or " triple") phosphate. 

 The latter is most common, and may appear in any de- 

 composing urine. It may be precipitated from fresh urine 

 in stellate crystals (Plate XXVII, Fig. 246) by adding 

 ammonia. More slowly deposited from alkaline urine, or 

 in disease, the crystals are prismatic, generally triangular, 

 with truncated ends. Sometimes the truncated ends are 

 bevelled, and the various lengths of the prisms give rise 

 to a variety of forms (Plate XXVII, Fig. 247). 



Triple phosphates are generally thought to proceed 

 from disintegrated albuminous, and chiefly nervous mat- 

 ter, but their clinica limportance is not fully settled. 

 They are found in cases of nervous depression, various 

 forms of dyspepsia, shock of the spinal cord, irritation of 

 the bladder, etc. 



In highly alkaline urine the triple phosphates are often 

 accompanied with pus and phosphate of lime. The latter 

 occurs as minute granules or dumb-bells, or in groups of 

 crystals (Plate XXVII, Fig. 248). They are dissolved by 

 acetic acid, which distinguishes them from uric acid. 



Oxalate of lime is deposited in small octohedra, gener- 

 ally appearing under the microscope as minute squares 

 with crossed lines proceeding from the angles, the upper 



