URINALYSIS. 153 



UROERYTHRIN. 



To a small amount of urine to be examined, add a 

 small amount of neutral acetate of lead, and if a yel- 

 low color appears, uroerythrin is present. (See Ty- 

 son for clinical significance or the Practice of Medi- 

 cine.) 



URATES. 



What is the brick-dust deposit in the urine? 



The murexide test for urates is a practical test. 

 Place a little urates in a tube and evaporate the same 

 after adding a little nitric acid. A yellow residue is 

 left. Add a little ammonia and the residue turns vio- 

 let, which forms the test for the urates or uric acid. 

 On the addition of potassium solution the color be- 

 comes blue. 



Give the formula for ammonium carbonate, also 

 ammonium carbamate. (See Medical Chemistry.) 



Test for bile in the urine : Take a small amount of 

 urine and put it in a test-tube. Now let a small 

 amount of commercial nitric acid run down the side 

 of the tube on the urine. If bile coloring matter is 

 present, a play of colors will be seen at the point of 



