286 



PRACTICAL PHYSIOLOGY 



can then be readily removed. To 10 c.c. of the urine to be tested add 



1 c.c. of a 10 per cent, solution of phosphoric acid. The test tube is 

 then fitted with a cork carrying a capillary tube and outlet tube, put 

 into a water bath at 65-70, connect with the water-pump and run 

 water so as to maintain a pressure of about 210 mm. of mercury. Allow 

 to run for about three-quarters of an hour. Temperature of bath not 

 to exceed 70. At the end of the heating period, stop suction, cool the 

 test tube under the tap, add a sufficient amount of previously 

 standardised soda solution to neutralise exactly the phosphoric acid 

 added, then transfer to a measuring cylinder and make up to 20 c.c. ; 



2 c.c. of the solution correspond to 1 c.c. of the urine. 



Estimation of Creatine. -Place in a small flask 10 c.c. urine and 



5 c.c. N. HC1. 

 Cover the mouth 

 of the flask with 

 tinfoil and heat 

 in the autoclave 

 at 115-120 for 

 twenty minutes. 

 If no autoclave is 

 available the flask 

 with small filter 

 funnel condenser 

 may be heated on 

 a water bath for 

 four to five hours. 

 Cool to room 

 temperature. 

 Add sufficient 

 caustic soda to 

 /TO PUMP neutralise the 

 acid added, 15 

 c.c. picric acid 

 solution and 5 

 c.c. 10 per cent, 

 caustic soda. 

 Allow to stand 

 for five minutes. 

 Wash the con- 

 tents of the flask 

 JIG. 198. Folin's apparatus for estimating ammonia. m f>o a 500 c c 



flask, make up to 



500 c.c., and proceed as for creatinine. The difference between this 

 result and that for creatinine previously determined represents the 

 amount of creatine present. 



Estimation of Ammonia. Folin Method. 25 c.c. urine are placed 

 in a long tube or cylinder, add 8-10 gms. sodium chloride or potassium 

 oxalate and 5 c.c. liquid paraffin (to prevent excessive frothing) and 

 finally 1 gm. anhydrous sodium carbonate. The tube or cylinder is 

 connected on one side with the air, which may be first passed through a 

 wash bottle, and on the other side with a flask or tube containing 20 c.c. 



N 



V H 2 SO 4 to absorb the ammonia liberated. It is well to add a few 





