URINE: QUANTITATIVE ANALYSIS. 393 



f solution of potassium bichromate. Bearing- this in mind the com- 

 putation is readily made by means of the following proportion in 

 which y represents the number of mm. of the solution of unknown 

 strength equivalent to the 8 mm. of the potassium bichromate solu- 

 tion : 



y : 8.1 : : 10 : x (mgs. of creatinine in the quantity of urine used). 



This proportion may be used for the calculation no matter what 

 volume of urine (5, 10 or 15 c.c.) is used in the determination. 

 The 10 represents 10 nig. of creatinine which gives a color equal 

 to 8.1 mm., whether dissolved in" 5, 10 or 15 c.c. of fluid. 



Calculate the quantity of creatinine in the twenty-four hour urine 

 specimen. 



XL Creatine. 



Folin-Benedict Method. To about 20 c.c. of urine in a 50 c.c. 

 volumetric flask, add 20 c.c. of normal hydrochloric acid and place 

 the flask in an autoclave at a temperature of 117-120 C. for one- 

 half hour. Add distilled water until the volume of the acid- 

 urine mixture is exactly 50 c.c., close the flask by means of a stopper, 

 and shake it thoroughly. Approximately neutralize 25 c.c. of this 

 mixture, introduce it into a 560 c.c. volumetric flask and deter- 

 mine its creatinine content according to Folin's Method (see p. 392). 



Calculation^- Calculate as explained on p. 392, and from this 

 value substract the value for the original content of creatinine before 

 hydrolysis. The difference between these two values will be the 

 creatine content of the original urine in terms of creatinine. 



XII. Indican. 



Ellinger's Method. This method for the quantitative determin- 

 ation of inclican is based upon the principle underlying Jaffe's test 

 for the detection of indican (see p. 280). The method is as follows : 

 To 50 c.c. of urine 1 in a small beaker or casserole add 5 c.c. of 

 basic lead acetate solution, mix thoroughly and filter. Transfer 40 

 c.c. of the filtrate to a separatory funnel, add an equal volume of 

 Obermayer's reagent (see p. 281) and 20 c.c. of chloroform and 

 extract in the usual manner. This extraction with chloroform 

 should be repeated until the chloroform solution remains colorless. 

 Now filter the combined chloroform extracts through a dry filter 



1 If the urine under examination is neutral or alkaline in reaction it should be 

 made faintly acid with acetic acid before adding the basic lead -acetate. 



