HANDBOOK FOR BIO-CHEMICAL LABORATORY. 101 



WITZ'S Test (HCl in the Contents of the Stomach). A watery 

 solution of methyl-anilin violet is first rendered blue, then 

 green, and ultimately decolorized by dilute inorganic acids. 



WURSTER'S Test (Tyrosin). A boiling watery solution of 

 tyrosin is colored red when treated with \% acetic acid and a 

 sodium nitrite solution, drop by drop. 



WURSTER'S Test (Tyrosin). Dissolve the tyrosin in hot 

 water and to the hot solution add some dry chinon. The 

 solution becomes deep ruby red, which remains for 24 hours 

 and then passes to brown. 



WURSTER'S Test (Hydrogen Peroxide). Paper soaked with 

 a solution of tetramethylparaphenylendiamine turns blue 

 violet with hydrogen peroxide. 



XANTHIN. See Hoppe Seyler, Weidel. 

 XAXTHO-PROTEIC Reaction (Proteids). See Mulder. 



v. ZALESKI'S Test (Carbon Monoxide in Blood). Mix 2 c.c. 

 of the blood with 2 c.c. water and 3 drops of a J saturated 

 copper sulphate solution. With normal blood u greenish- 

 brown precipitate is produced, while if the blood contains CO 

 a brick -red precipitate is obtained. 



ZELLER'S Test (Melanin in Urine). A urine containing 

 melanin gives, when treated with bromine water, a yellow pre- 

 cipitate, which gradually turns black. 



ZOUCHLOS'S Test (Albumin). The reagent consists of 100 

 parts 10$ potassium sulpho-cyanide solution and 20 parts 

 acetic acid. When this reagent is added, drop by drop, to a 

 solution of albumin, a marked cloudiness is observed. 



ZWE:N:GER J S Test (Cholesterin). See Cholesterin Reactions 

 Xo. 1. 



