116 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



mass/ which later becomes brittle, twice with distilled water. 

 With some care this may easily be done almost without any 

 loss. : Pour over the precipitate a few cubic centimeters of 

 water and dissolve it by adding sodium hydroxide solution. 

 The deep-blue solution is warmed on the wire gauze until the 

 color has disappeared, then poured into a test-tube, cooled, 

 and copper sulphate solution cautiously added. The color is 

 not always a pure violet, but often only a dirty red or even 

 yellowish red. Often 10 to 15 cc. of the urine will give the 

 reaction. 



If the urine contains albumin it must previously be treated 

 with sodium acetate and enough ferric chloride to give the 

 fluid a blood-red color, the acid neutralized with dilute 

 sodium hydroxide solution and heated to boiling. The 

 filtrate must give neither a turbidity nor a blue color with 

 acetic acid and potassium ferrocyanicle (a very faint blue 

 color is very difficult to avoid and may be disregarded). 



If the urine contains mucin or nucleoalbumin it must be 

 precipitated with a little neutral lead acetate solution, so- 

 that a heavy flocculent precipitate is formed. Then after 

 filtration precipitate with phosphotungstic acid, either at 

 once or after treatment with sodium acetate and ferric chlo- 

 ride in case the urine also contains albumin. In the case of 

 animal urines the previous treatment with lead acetate solu- 

 tion is advisable. 



2. For urines containing considerable urobilin v. Aldor l 

 has modified this method as follows: 8 to 10 cc. of urine are 

 made acid with a few drops of hydrochloric acid, precipitated 

 with phosphotungstic acid and centrifuged. The super- 

 natant fluid is poured off, the precipitate covered with abso- 

 lute .alcohol and again centrifuged. This is repeated until 

 the alcohol remains entirely colorless, then suspend the pre- 



1 Berliner Klinische AVochenschr. , 1899, Nos. 35 and 36. 



