URINE 



333 



Folin absorption tube, and titrate the remaining acid with N/10 

 alkali. 



Subtract the volume of alkali used in titration from the 

 original volume of N/10 acid. The result is the amount of N/10 



Air 



FIG. 4. FOWN'S APPARATUS FOR ESTIMATING AMMONIA. 



A. Wash bottle containing acid. 



B. Tall aerometer cylinder containing urine. 



C. Bottle containing standard acid. 



D. Calcium chloride tube, loosely packed with cotton wool, to prevent any sodium 



carbonate being carried over into C. 



E. Folin's absorption tube, to bring the air into intimate contact with the acid. 



