330 



ANALYSIS OF URINE. 



[CH. XIII. 



and the results obtained by it are only of approximate value for the ammon'a 

 figure. It will be described in connexion with the estimation of amino-acids. 



Of the two methods described below, the author now always employs Van 

 Slyke's, which is much more rapid than Folin's. The author is convinced 

 that failures to obtain correct results are either due to inattention to essential 

 details or to the use of an imperfect suction pump. An apparatus that sup- 

 plies air under a good pressure is a most valuable adjunct to a modern bio- 

 chemical laboratory. 



398. The estimation of ammonia by Folin's method. 



, U-[LTO PUN,. 



Fig. 43. Folin'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. 



Use the apparatus shewn above.* 



* The parts of the apparatus can be obtained from Messrs. Baird and 

 Tatlock (London). 



