152 THE URINE. 



Excessive acidity 1 of the urine causes, in time, an irri- 

 tation of the urinary passages, and is favorable to the 

 formation of uric acid concretions. Continued alkalinity 

 makes a sediment in the urine, and tends to produce phos- 

 phatic calculi. It also produces irritation or inflammation 

 of the mucous membrane. 



338. Test the reaction of urine with sensitive litmus- 

 paper, and if alkaline determine whether it is caused by 

 ammonium carbonate by the paper's turning red again 

 after drying, or whether a sodium or potassium compound 

 is the alkali by the paper's remaining blue on drying. 



339. To DETERMINE THE ACIDITY OF URINE. To 50 cubic 

 centimeters in a flask add 25 cubic centimeters of l / 10 normal 

 sodium hydrate, and heat to boiling, then remove the flame. 

 Thereupon add 25 cubic centimeters of barium chlorid solution 

 of about 5 or 10 per cent. Filter through a dry filter, and take 

 50 cubic centimeters of the filtrate, corresponding to 25 cubic 

 centimeters of the urine, for testing. Dilute it to about 250 cubic 

 centimeters with water, add a few drops of phenolphthalein for 

 an indicator, then from a burette, Vio normal sulphuric acid until 

 the red color is just destroyed. Subtracting the number of cubic 

 centimeters of acid used from 12.5, the number of cubic centimeters 

 of standard sodium hydrate in the half of the liquid used, gives 

 the number of cubic centimeters of sodium hydrate neutralized by 

 the acid in 25 cubic centimeters of urine. 



340. Collect the urine of the day in periods of three hours 

 each and determine the variations in its acidity. 



341. Take internally sodium acetate in 2 to 3 

 gramme doses, and note its effect upon the reaction of 

 the urine. 



UKEA. 



About 86 per cent, of the nitrogen in the urine of a 

 healthy man has been found to be in the urea, CO(NH 2 ).,. 

 Under pathological conditions, however, it may vary greatly 



