ADVANCED CHEMICAL PHYSIOLOGY 



281 



The ordinary ammonia-absorption apparatus is modified as shown in 

 the diagram. The constrictions in all three tubes should be placed at 

 such a level that the capacity of the lower bulb is about three times 

 the volume of the liquid within it. If this precaution be taken the use 

 of toluol is unnecessary in most cases. 



To complete the experiment in the times given the pump used should 

 be capable of drawing air through the apparatus at a rate of not less 

 than 5 litres per minute. Water bath temp. 40 C. 



Into tube A place 20 c.c. water, 5 c.c. urine, and 3-5 gms. soy bean 



To Pump 



Wash-bottle containing 

 dilute H 2 S0 4 



$//,SQ 



FIG. 196. 



meal (varying amounts are required according to the condition of the 

 bean ; a slight excess will not vitiate the result). Mix the contents of 

 the tube and insert the central tube and glass beads as shown, 

 immerse bulb in water bath, then connect up to collecting tubes con- 

 taining a known amount of decinormal acid. Start the pump and 

 introduce about 2 c.c. of a saturated solution of sodium carbonate from 

 a pipette by holding the nozzle of the pipette at X and opening the clip. 

 Close the clip and aerate for forty minutes. 



Calculation. The amount of decinormal acid neutralised by the 



