DISEASES OF THE URINARY SYSTEM. 211 



Name some important substances found in disease. 



Some of the normal constituents may be abnormally increased, 

 as urea, etc., phosphates, chlorides, etc.; in other cases, albumin, 

 bile, blood, sugar, pus, epithelial casts may be present. 



How are you to proceed to examine the urine ? 



If possible collect all the urine passed during the twenty-four 

 hours and take a sample of the mixture. 



Note carefully all the physical properties, and then test for 

 special substances. 



Give a test for the phosphates. 



The earthy or alkaline phosphates are discovered by heating 

 a quantity of urine in a test-tube, when a cloudy appearance is 

 presented; this milky appearance disappears on the addition of 

 acetic or nitric acid. 



How may albumin be discovered in the urine? 



Heat to boiling some urine in a test-tube; a milky appearance 

 shows the presence of albumin, provided it does not disappear on 

 the addition of nitric acid. 



What is the test for bile ? 



Heat till yellow some nitric acid containing small pieces of 

 wood, and then cool; now float some urine on the cold acid. If 

 bile pigments are present, a green band forms at the junction which 

 shades into blue, red, violet, yellow (Gmelin's test). 



Give the test for urea. 



If the urine contains urea in excess, the rhombic-shaped crys- 

 tals of the nitrate of urea separate, when nitric acid is added to a 

 cold concentrated solution of urine. This is best appreciated by 

 using a thin layer on a plate or watch-glass. 



How may blood be discovered? 



If the urine is red, smoky, or dark in color, suspect the pres- 

 ence of blood. 



1. Heat, about to boiling, alkaline urine to which potassium 

 hydrate has been previously added, and a red precipitate is produced. 



2. Mix oil of turpentine and tincture of guaiac; now add as 

 much urine as the mixture, shake carefully, and after a time 8 

 bluish or greenish color on top shows the presence of blood. 



