50 



amount from the oxidation of the phosphorus of nerve 

 tissues. 



237. To a small amount of urine add about half its volume 

 of nitric acid, and then add a little ammonium molybdate 

 solution and boil. A canary-yellow crystalline precipitate 

 of ammonium phospho-molybdate may appear. The pre- 

 cipitate may appear slowly and if necessary, the tubes should 

 be kept undisturbed for a few hours. In a very dark urine 

 the precipitate may be of a brown instead of a yellow color. 

 Make sure that the herbivorous urine is of an acid reaction 

 before adding the ammonium molybdate. 



238. To urine add half its volume of ammonia and allow 

 it to stand, a precipitate of earthy phosphates is formed. 

 Filter and test the filtrate with ammonium molybdate. This 

 method separates the earthy from the alkaline phosphates. 



239. To urine add half its volume of baryta mixture ; a 

 copious precipitate. Filter and test the filtrate with am- 

 monium molybdate. No precipitate should occur as the 

 baryta mixture precipitates the phosphates as well as the 

 sulphates and carbonates. 



240. Use a little magnesia mixture instead of the baryta 

 mixture. Filter and test the filtrate with ammonium 

 molybdate. The magnesia mixture is composed of mag- 

 nesium sulphate and ammonium chloride, of each one part, 

 ammonia water i part and distilled water 8 parts. 



241. To urine add a few drops of acetic acid and then a 

 few drops of uranium acetate, a yellow precipitate of ura- 

 nium and ammonium double phosphate is formed. 



242. Centrifugal analysis of urine. The chemical con- 

 stituents of urine, both normal and abnormal, may be esti- 

 mated by the centrifugal method. By the use of percentage 

 tubes an approximate estimation of certain of the constitu- 

 ents may be obtained. These tubes are graduated in tenths 

 of a cubic centimeter up to 10 cc. The lower portion of 

 the tube is drawn out in a conical form, and fractions of the 



