148 THE URINE. 



ease. Its variation gives indications of the progress of the 

 disease. The volume will be also affected by the amount 

 of drink or liquid food and, in general, varies inversely 

 with the perspiration. 



From the presence of ferments, the urine begins to 

 undergo a change after it has stood a few hours. The re- 

 action becomes alkaline, owing to the production of am- 

 monium carbonate from the urea, and this precipitates 

 some of the solids, so that the liquid loses its transparency. 

 This and other decompositions produce disagreeable odors. 



The odor of normal urine is characteristic. Certain 

 foods and medicines change this; e.g., oil of turpentine 

 gives an odor of violets. When it putrefies the odor is 

 ammoniacal and offensive. In cystitis it is ammoniacal 

 when passed. In suppurative diseases the odor may be 

 putrid. 



Fresh, normal urine is clear, but after standing a 

 short time a cloud of mucus appears. Pathologically it 

 may be cloudy with matters which settle as a sediment. 

 They will be discussed under that subject. 



The color of urine is normally some shade of yellow, 

 varying from nearly colorless to reddish yellow. The 

 former is true of urines containing much water, and the 

 latter where the urine is concentrated and of high specific 

 gravity. The latter is constant in febrile conditions and 

 their severity can here often be judged from the color. 

 Pathologically the urine assumes many other shades. 

 Presence of blood gives a red or, when methaBmoglobin is 

 present, a brown. Jaundice gives a greenish cast or 

 brownish green; melanotic cancer, almost black; typhus 

 or cholera, sometimes blue, from indigo formed by decom- 

 position. Some medicinal or poisonous substances change 

 the color; thus senna or rhubarb gives a reddish or brown- 



