EXAMINATION OF THE URINE. 107 



2. Add to the phenol solution one-fourth its volume of 

 ammonia, then a few drops of a solution of chloride of lime 

 (bleaching-powder), and warm gently, but not to boiling: blue 

 or green color. 



3. Add a few drops of Millon's reagent and heat to boil- 

 ing: intense dark-red color or dark-red precipitate. The reac- 

 tion is very distinct even at 1 : 60,000, but at such great 

 dilution only a delicate rose-color appears. All benzene 

 derivatives which contain a hydroxyl group in the aromatic 

 residue give a similar reaction (0. Nasse). 



4. Addition of bromine-water produces at first a gelatinous 

 precipitate of monobromphenol or dibromphenol, which is 

 characterized by a very penetrating odor. On further addi- 

 tion of bromine yellowish-white tribromphenol, C 6 H 2 Br 3 OH, 

 is formed. In dilute solutions this last compound is at once 

 formed. 



Of the reactions, 3 and 4 are the most delicate and the 

 most used. 



After the medicinal use of phenol it may be found in the 

 urine. Horse-urine and pathological urine contain cresol 

 instead of phenol, or at least in much larger quantity. The 

 reactions of cresol (paracresol) are similar to those of phenol, 

 but less marked. The color with ferric chloride is not blue, 

 but a dirty gray. This is partly due to the fact that the 

 cresol is far less soluble in water than the phenol. 



(b) PHENYL SULPHURIC ACID OR CRESYL SULPHURIC ACID. 



Detection of Phenol in Urine. 



Phenol and cresol are never found as such in urine, but 

 always combined with sulphuric acid in the form of the potas- 

 sium salts (so-called conjugate or ethereal sulphates), 



or 



Potassium phenyl sulphate Potassium cresyl sulphate 



