456 



PHYSIOLOGICAL CHEMISTRY. 



Practically, the operation is conducted as follows : 100 grammes of 

 sodium hydroxide are dissolved in 250 c.c. of water, and to this 

 cooled solution are added 25 c.c. of pure bromine, when sodium 

 hypobromite is formed, leaving, however, an excess (over one-half) 



FIG. 41. 



Apparatus for the volumetric estimation of urea. 



of the sodium hydroxide in an unaltered condition. (The solution 

 easily decomposes, and should, therefore, be freshly prepared for 

 analysis.) 



The apparatus required (Fig. 41) consists, in its most simple form, 

 of a wide-mouth bottle, A; a small test-tube, B, of about 10 c.c. 

 capacity; a glass cylinder, c, and a graduated burette, D. 



Into a bottle is fitted a perforated cork, which is connected by 

 means of tubing with the burette. 5 c.c. of urine are introduced 

 into the test-tube and 20 c.c. of the alkali hypobromite solution into 

 the bottle, care being taken not to bring the liquids in contact with 

 each other. The graduated burette is lowered in the cylinder, until 

 the zero-mark is on a level with the surface of the water in the 



