LESSON XXIII. 

 URINE. 



1. DETERMINE the specific gravity of urine by 

 means of the urinometer. 



2. Test the reaction of fresh urine with litmus 

 paper, it will be acid; this is due to the pre- 

 sence of acid salts mainly of acid sodium phos- 

 phate, and not to free acid. 



3. Put 200 c.c. of urine in a warm place, and ob- 

 serve from time to time. 



a. It will, after twenty-four or more hours, lose 

 its acid reaction, and become alkaline. 

 Gently warm the litmus paper turned blue 

 by the urine, the blue colour will disappear, 

 shewing that the alkalinity is due to the 

 presence of ammonia or a salt of ammonium. 



b. It will gradually become cloudy, and yield a 

 deposit of various salts. 



c. Its odour will become putrefactive. 



The urine has undergone alkaline fermenta- 

 tion. 



