EXAMINATION OF THE URINE. 115 



reaction, and heat to boiling. A turbidity or precipitate 

 shows the presence of albumin (mucin remains in solution). 



5. Acidify with acetic acid and add a few drops of potas- 

 sium ferrocyanide solution: cloudiness proves the presence 

 of albumin (a very delicate reaction, but only available when 

 the urine remains clear after the addition of acetic acid alone; 

 moreover, it is also given by albumose). 



The precipitated albumin may be filtered off, washed, and 

 used for the color reactions (see page 4). 



The examination for both globulin and albumin is carried 

 out as in the case of blood-serum (page 59), the urine being 

 previously made alkaline with ammonia and filtered. 



XV. DETECTION OF ALBUMOSES (PEPTONE). 



To detect albumoses (peptone) we precipitate with phos- 

 photungstic acid according to Hofmeister and try the biuret 

 reaction with the precipitate, after the albumoses have been 

 set free by means of baryta or (simpler) by caustic soda. The 

 presence of urobilin, which is carried down in the precipitate 

 with phosphotungstic acid and also gives the biuret reaction, 

 complicates matters. If any considerable amount of uro- 

 bilin is present, it must be removed (most readily with abso- 

 lute alcohol) before trying the biuret reaction with the pre- 

 cipitate. When the amount of urobilin is small and the 

 urine is not highly colored, this may be dispensed with and 

 method 1 may be used. 



1. Acidify 50 cc. of urine (for practice use urine to which 

 0.25 to 0.5 g. of the commercial peptone to the liter has been 

 added) in a beaker with a few cubic centimeters of hydro- 

 chloric acid, precipitate with phosphotungstic acid, and heat' 

 on the wire gauze. In a few minutes the precipitate forms a 

 resinous mass, which sticks to the bottom of the vessel. As 

 soon as this has occurred, pour off the supernatant, nearly 

 clear, liquid as completely as possible and rinse the resinous 



