THE URINE 193 



V. DETERMINATION OF AMMONIA. 



Place in the crystallizing-dish of the Schlosing's apparatus 

 25 cc. of filtered urine and in the porcelain dish of the same 

 apparatus 10 cc. of fifth-normal acid. Then add to the 

 urine about 25 cc. of milk of lime (one part by weight 

 of calcium hydroxide shaken with twelve parts of water) and 

 quickly put on the cover. After forty-eight to seventy-two 

 hours wash out the contents of the upper dish into a beaker, 

 mix thoroughly, and titrate with tenth-normal ammonia solu- 

 tion. The difference corresponds to the ammonia evolved 

 from the urine. One cubic centimeter of fifth-normal acid 

 = 0.003414 g. NH 3 . If 25 cc. of urine were used and fifth- 

 normal acid, then the product of the difference in cubic 

 centimeters by 0.013656 gives the quantity of ammonia in 

 100 cc. of urine. Test any water which has condensed on the 

 top or walls of the apparatus for an alkaline reaction. If it 

 reacts alkaline, rinse the apparatus with water and titrate it 

 also. 



VI. DETERMINATION OF UREA. 



(a) According to Morner and Sjoqvist. Mix in a flask 

 5 cc. of urine, 5 cc. of baryta mixture (10 g. barium chloride, 

 3-4 g. barium hydroxide, and 100 cc. of water), and add 

 100 cc. of a mixture of alcohol and ether (two volumes of 97 

 per cent, alcohol and one volume of ether) . Let stand till next 

 day, filter, wash with the alcohol-ether mixture, evaporate 

 at a gentle heat, and when the volume has reached 25 cc. 

 add some water and some milk of magnesia (one part of 

 burnt magnesia and twelve parts of water), and heat, to 

 drive out ammonia, till the vapor no longer reacts alkaline. 

 Then wash the fluid together with the precipitate into a 

 Kjeldahl flask, add some dilute sulphuric acid, then 10 cc. 

 of the concentrated acid, determine the nitrogen as usual 



