URINE 289 



tubing, and a stopper. In the other neck of the Woulff bottle 

 fix a cork through which passes the narrow tube of a CaCL 

 tube. Charge the bulb of the CaCl 2 tube with glass pearls. 



Prepare the Woulff bottle by running into it over the glass 

 pearls in the calcium chloride tube, 50 c.c. N/10 hydrochloric 

 acid measured with a pipette, add 2-3 drops alizarine red and 

 connect the bottle by the other neck with the delivery tube of 

 the distilling apparatus. Set the digestion flask on a ring over 

 the flame and make sure that all connections fit properly. Add 

 a small quantity of talcum powder to prevent irregular boiling 

 (bumping) but not more than the amount that can be taken up 

 on the tip of a knife blade. Add a drop of alizarine and then 

 about 50 c.c. of sat. NaOH to neutralize the sulphuric acid. 

 In adding the alkali, the flask should be tilted somewhat and 

 the sodium hydrate poured down the side of the tube so that 

 it will form a layer underneath the acid. This is to avoid 

 possible loss of ammonia. Stopper the flask immediately, make 

 sure that the stopper fits tightly, and rotate the flask gently 

 so as to mix the contents thoroughly. If the liquid does not 

 turn pink or purple, add more alkali as above. Distill the lib- 

 erated ammonia into the standard acid. When about % of 

 the water has distilled over, remove the Woulff bottle and test 

 the next drop of distillate for ammonia by letting it fall into a 

 small beaker containing distilled water and a drop of alizarine. 

 If the indicator turns pink, replace the Woulff bottle and con- 

 tinue the" distillation until the liquid coming over no longer 

 contains ammonia. When the ammonia is all over, discontinue 

 the distillation, rinse down the glass pearls with distilled 

 water, and titrate the excess of N/10 HC1 with standard alkali. 



Subtracting the amount of alkali used from the total acid 

 (50 c.c.) gives the volume of acid neutralized by the ammonia. 



Multiply this figure by the weight of nitrogen in 1 c.c. of 

 N/10 ammonia (1.401 mg.). This gives the weight of nitrogen 

 in 5 c.c. urine. Calculate the weight of nitrogen in the 24 hour 

 sample. 



