240 THE MICROSCOPIST. 



and towards the close waxy or fatty, often containing 

 many oil-globules (Plate XXVI, Fig. 193). 



2. Precipitates from Solution. (1.) Urate of ammonia. 

 This is generally an amorphous deposit, in irregular groups 

 of molecules, but with an alkaline fermentation sometimes 

 crystallizes (Plate XXYI, Fig. 194). Some regard this 

 as urate of soda, or a mixture of urates of potash, soda, 

 and ammonia. 



Its color varies from light pink to brickdust color. It 

 is deposited 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. 



('!.} Uric acid may occur from an acid fermentation 

 dissolving urates of soda or ammonia. It is a yellow, 

 reddish, or brown sediment of crystals, which assume 

 different forms, as rhomboid tablets with obtuse angles, 

 or of the shape of a whetstone (Plate XXVI, Fig. 195). 



When slowly precipitated, it may form druses of four- 

 sided prisms (Plate XXYI, Fig. 196). When precipitated 

 from fresh urine by the addition of muriatic acid, the 

 crystals are large, and often of varying shapes. 



They may be tested by dissolving in potassa, and re- 

 precipitating by muriatic acid, when they assume the 

 shape of Fig. 197, Plate XXYI. 



They originate from waste, excess of nitrogenous food, 

 defective assimilation, congestions of the kidney , or chronic 

 disease of the respiratory organs. 



(3.) Ammonio-phosphate of magnesia, triple phosphate, 

 may be precipitated from fresh urine in stellate crystals 

 (Plate XXVII, Fig. 198) by adding ammonia. When 

 more slowly deposited from alkaline urine, or in diseased 

 states of the system, the crystals are prismatic, generally 

 triangular, with obliquely truncated ends. Sometimes the 

 terminal edges are bevelled, and the varying lengths of 

 the prisms give rise to a variety of forms (Plate XXVII, 

 Fig. 199). They are generally thought to proceed from 



