98 CHEMICAL PHYSIOLOGY. 



(d.) Mix the urine gradually with the hypobromite solu- 

 tion by gently tilting over the flask, and ultimately move 

 the flask so as to wash out the test-tube with the hypo- 

 bromite solution. Gas is rapidly given off, the CO 2 is 

 absorbed by the caustic soda, while the N is collected in the 

 graduated measuring tube. 



(e.) Place the flask in a jar of water at the same tempera- 

 ture as that in the tall jar, and slightly lower the measuring 



tube. After all 

 effervescence has 

 ceased, and when 

 the N collected in 

 the collecting tube 

 has cooled to the 

 temperature of 

 the room i.e., 

 in three to five 

 minutes raise 

 the collecting tube 

 until the fluid in- 

 side and outside 

 stands at the same 

 level. Read off 

 the graduated 

 tube ; this gives 

 the percentage of 

 urea. 



It is to be re- 

 membered that 

 other bodies in 

 the urine, such as 

 uric acid (urates) 

 and creatinin 



bu * not KPP 



acid also vieid 

 nitrogen by this 

 process ; further, 



Fig. 24. G. Steele's apparatus for urea. A, 



C, burette ; D, vessel with water ; E, vessel 

 with water to cool A. 



, 



that only about 92 per cent, of the N of the urea is given 

 off in the above processes. These sources of fallacy are, 

 however, taken into account in graduating the apparatus. 



8. Steele's Apparatus. This is practically the same apparatus, 



