47 



Chlorides. Fill the graduated tube to the 10 ec. 

 mark with the uriue. Add 15 drops or 1 cc. of nitric acid 

 to prevent precipitation of the phosphates. Then fill to 

 the 15 cc. mark with the silver nitrate solution (1 to 8). 

 Invert the tube several times to thoroughly mix the re- 

 agents. Revolve in the centrifuge for intervals of three 

 minutes until the precipitate no longer settles. The aver- 

 age amount of precipitate for man is from 0.5 cc. to 0.8 cc. ; 

 for the horse about 0.5 cc. The value of each 0.1 cc. is 1.3 

 of a gram of NaCl per 1000. 



Sulphates. These are estimated as insoluble salts 

 of barium. Fill the graduated tube to 10 cc. mark with 

 fresh urine and add 5 cc. barium chloride solution, (4 

 parts barium chloride, 1 part hydrochloric acid, 16 parts 

 distilled water). 



The amount of precipitate for man and horse is about 

 .075 cc. normally. The value of each 0.1 precipitate is 

 2.4 grams of SOg. 



In the above tests write down in your notes the 

 amount '.of each constituent for .the 24 hours .considering 

 ■ '.'.1250 ccr'as thi? tptatiamomit of iirine passed. 

 Quantitative Estimation of Uric Acid. This estimation is 

 difficult and time-consuming and is generally regarded as inex- 

 pedient for clinical purposes. The following, methods are de- 

 scribed because they are more suitable for clinical work although 

 less accurate than the more elaborate methods of Salkowski, Lud- 

 wig, Hopkins and others. 



Ruhemann's Uricometer for the rapid estimation of uric 

 acid consists of a graduated tube with a glass stopper. It is a 

 colorimetric method, in which iodine with carbon bisulphide serve 

 as indicators. 



The following directions accompany each apparatus : 

 Fill the glass tube to the lowest mark S with carbon bisul- 

 phide. (It is not necessary for the tube to be quite dry, but 

 there must be no drop of liquid at the bottom) . 



The lowest part of the convexity . (double meniscus) has to 

 be even with mark S, see diagram. 



Add a solution consisting of 1.5 gm. iodine; 1.5 gm. potas- 

 sium iodide; 15 gm. absolute alcohol and 185 gm. distilled 

 water. 



