726 UKINE. 



The alkali salts of phenol- and cresol-sulphuric acids crystallize in 

 white plates, similar to mother-of-pearl, which are rather freely soluble 

 in water. They ,are soluble in boiling alcohol, but only slightly soluble 

 in cold alcohol. On boiling with dilute mineral acids they are decom- 

 posed into sulphuric acid and the corresponding phenol. 



Phenol-sulphuric acids have been synthetically prepared by BAUMANN 

 from potassium pyrosulphate and potassium phenolate or p-cresolate. 

 For the method of their preparation from urine, which is rather compli- 

 cated, and also for the known phenol reactions, the reader is referred 

 to other text-books. The quantitative estimation of the phenols from 

 these etheral sulphuric acids is now ordinarily done by the following 

 methods : 



KOSSLER and PENNY'S method with NEUBERG'S l modification. The 

 liquid containing phenol is treated with N/10 caustic soda until strongly 

 alkaline, warmed on the water-bath in a flask with a glass stopper, and 

 then treated with an excess of N/10 iodine solution, the quantity being 

 exactly measured. Sodium iodide is first formed and then sodium 

 hypoiodite, which latter forms tri-iodophenol with the phenol accord- 

 ing to the following equation: 



On cooling, acidify with sulphuric acid and determine the excess of iodine 

 by titration with N/10 sodium thiosulphate solution. This process is 

 also available for the estimation of paracresol. Each cubic centimeter 

 of the iodine solution used is equivalent to 1.5670 milligrams of phenol 

 or 1.8018 milligrams of cresol. As the determination does not give any 

 idea as to the variable proportions of the two phenols, the quantity of 

 iodine used must be calculated as one or the other of the two phenols. 

 Before such a determination is carried out, the concentrated urine is 

 first distilled after acidification with sulphuric acid and the distillate 

 purified by precipitation with lead, and distilled again (NEUBERG). 

 MOOSER has raised objections against the use of sulphuric acid and rec- 

 ommends instead the use of phosphoric acid. In regard to the dispute 

 which has arisen between NEUBERG and MOOSER 2 as well as to the details 

 of NEUBERG'S method we must refer to the original publications and to 

 larger handbooks. 



For the separate estimation of phenol and p-cresol in the urine a 

 special method has been suggested by SIEGFRIED and ZIMMERMANN. S 

 The principle of the method consists in the two following estimations: 

 1. The quantity of bromine necessary to convert the phenol and cresol 

 into tribromphenol and tribromcresol is determined. 2. The quantity 

 of bromine necessary to convert the phenol into tribromphenol and the 



1 Kossler and Penny, Zeitschr. f. physiol. Chem., 17; Neuberg, ibid., 27. 



2 Mooser, Zeitschr. f. physiol. Chem., 63, with Liechti, ibid., 73; Neuberg and 

 Hildesheimer, Bioch. Zeitschr., 28; Marie Hensel, Zeitschr. f. physiol. Chem., 78. 



8 Siegfried and Zimmermann, Bioch. Zeitschr., 29, 34 and 38; see also Ditz and Bar- 

 dach, ibid., 37 and 42. 



