URINE. 28l 



2. Obermayer's Test. Nearly fill a test-tube with a mixture 

 composed of equal volumes of Obermayer's reagent 1 and the urine 

 under examination. Add 2-3 c.c. of chloroform, place the thumb 

 over the end of the test-tube and shake thoroughly. How does 

 this compare with Jarre's test? 



3. Giirber's Reaction. To one volume of the urine under ex- 

 amination and two volumes of concentrated hydrochloric acid in a 

 test-tube add 2-3 drops of a i per cent solution of osmic acid and 

 2-3 c.c. of chloroform and shake the tube and contents thoroughly. 

 Compare the color with those obtained in Jarre's and Obermayer's 

 tests. 



An excess of osmic acid does not affect the reaction. Occa- 

 sionally better results are obtained if the solution of osmic acid 

 is added directly to the urine before the addition of the hydro- 

 chloric acid. If the urine under examination be strongly colored 

 or of high specific gravity it should first be treated with basic lead 

 acetate (one-eighth volume). The precipitate is then removed by 

 filtration and the resulting filtrate used in making the test for 

 indican. 



4. Rossi's Reaction. To equal volumes of concentrated hydro- 

 chloric acid and the urine under examination, in a test-tube, add 

 i drop of a 10 per cent solution of ammonium persulphate and 2-3 

 c.c. of chloroform. Agitate the mixture vigorously and note the 

 color of the chloroform. Compare this result with those obtained 

 in the other indican tests. 



5. Lavelle's Reaction. To 10 c.c. of urine in a test-tube add 

 2-3 c.c. of Obermayer's reagent 1 and a similar volume of concen- 

 trated sulphuric acid. (During the addition of the acid the tube 

 should be held under running water in order that the temperature 

 of the mixture may not rise too high.) Add 2-3 c.c. of chloro- 

 form, shake the tube vigorously, and observe the depth of color 

 assumed by the chloroform. 



The sponsor for this reaction claims it to be the most satisfactory 

 of the indican tests. 



CO-NH-CH.-COOH. 



HIPPURIC ACID, 



1 Obermayer's reagent is prepared by adding 2-4 grams of ferric chloride to 

 a liter of concentrated HC1 (sp. gr. 1.19). 





