XVI.] 



THE URINE. 



109 



swarms with bacteria, and it has an ammoniacal odour, which is 

 due to the splitting up of the urea, thus — 



CON2H4 + 2H2O = (NH4),C03. 



The urea is split up by a ferment formed by the micrococcus 

 urex. The carbonate of ammonium makes the urine alkaline, and 

 the earthy phosphates are precipitated because they are insoluble in 

 an alkaline urine. The phosphate of lime is precipitated as such 

 (amorphous), while the phosphate of magnesia unites with the 

 ammonia and is precipitated as ammonio-magnesic phosphate or 

 triple phosphate (MgNH^PO^ + 6H2O). Part of the ammonia 

 escapes, and in addition to that united to the magnesic phosphate, 

 some unites with uric acid to form urate of ammonium. 



ElO. 54.— Deposit in Ammoniacal Urine (Alkaline Fermentation), a. Ammonlo- 

 magnesium phosphate ; d. Acid ammonium urate ; c. Bacterium urese. 



N.B. — Although urine may be kept " sweet " for a long time in 

 perfectly clean vessels, still when mixed with decomposing matter 

 it rapidly putrefies. Insist that all urinary vessels be scrupulously 

 clean; and that all instruments introduced into the bladder be 

 properly purified by carbolic acid or other antiseptic. 



(a.) Place some normal urine aside for some days, in a warm 

 place. Observe it from day to day, noting its reaction, change of 

 colour, transparency, odour, and any deposits that may form in it. 

 Examine the deposit microscopically (figs. 53, 54). 



Fermentation is liasteyied by a high temperature, and especially 

 if the urine be passed into a contaminated vessel, or the urine 

 itself contain blood, much mucus or pus. It is retarded in a very 

 acid and concentrated urine. 



