188 QUANTITATIVE ANALYSIS. 



add a few drops of an alcoholic solution of phenol phthalei'n 

 and a piece of granulated zinc. Connect the flask by means 

 of a two-hole rubber stopper with a Reitmeyer bulb-tube 

 attached to a Liebig condenser and with a bent safety-tube. 

 Attach to the other end of the condenser a delivery-tube 

 reaching to the bottom of a 250-cc. Erlenmeyer flask, which 

 serves as a receiver. Place a carefully measured quantity of 

 the N/5 hydrochloric acid (for 5 cc. of urine 25 cc. of the acid) 

 in the receiver with a little of the cochineal solution and, if 

 necessary, add a little water, so that the end of the delivery- 

 tube dips below the surface of the liquid. Then add through 

 the funnel-tube sufficient of the strong sodium hydroxide 

 solution to make the contents of the distillation-flask dis- 

 tinctly alkaline. Mix the contents of the flask during this 

 addition by means of a gentle rotary motion. Then distil 

 off about 150 cc. of the liquid and titrate the contents of 

 the receiver with the N/10 ammonia solution. 



Example: 5 cc. of urine, specific gravity 1.027, were taken, 

 25 cc. of N/5 acid placed in the receiver required 6.2 cc. of 

 the N/10 ammonia to completely neutralize after the distilla- 

 tion. 



25 cc. of N/5 HC1 = 50 cc. of N/10 NH 3 . 



/. 50 cc. 6.2 cc. = 43.8 cc. NH 3 obtained from the urine. 

 43.8X0.001404 



5X1.027 



1.197% N in the urine. 



III. DETERMINATION OF URIC ACID. 



This determination is based on the precipitation of the 

 uric acid in the presence of magnesium salts by an ammonia- 

 cal silver solution as silver magnesium urate, and the solu- 

 bility of silver chloride in ammonia. To 200 cc. of the urine, 

 whose specific gravity must not exceed 1020 (if it is more 



