730 URINE. 



ments are produced, a behavior which PORCHER and HERVIEUX l have observed in 

 several alkyl-substituted indols. 



An increased elimination of indican has been observed in many 

 diseases, 2 and in these cases the quantity of phenol eliminated is also 

 generally increased. A urine rich in phenol is not always rich in indican. 



The potassium salt of indoxyl-sulphuric acid, which was prepared 

 pure by BAUMANN and BRIEGER from the urine of dog fed on indol, 

 has subsequently been prepared synthetically by BAUMANN and THESEN, S 

 by fusing phenyl-glycine-orthocarboxylic acid with alkali and then from 

 this producing the indoxylsulphate by means of potassium pyrosulphate. 

 It crystallizes in colorless, shining plates or leaves which are easily soluble 

 in water, but less readily in alcohol. It is solit by mineral acids into 

 sulphuric acid and indoxyl. The latter without access of air passes into 

 a red compound, indoxyl red, but in the presence of oxidizing reagents 

 is converted into indigo blue: 2C8H 7 NO+2O = Ci6HioN 2 O2+2H2O. The 

 detection of indican is based on this last fact. 



For the rather complicated preparation of indoxyl-sulphuric acid as 

 potassium salt from urine the reader is referred to other text-books. 

 For the detection of indican in urine in ordinary cases the following 

 method of JAFFE-OBERMAYER, which also serves as an approximate test 

 for the quantity of indican, is sufficient. 



JAFFE-OBERMAYER'S Indican Test. JAFFE uses chloride of lime as 

 the oxidizing agent, while OBERMAYER employs ferric chloride. Other 

 oxidizing agents have been suggested, such as potassium permanganate, 

 potassium dichromate, alkali chlorate, and hydrogen peroxide (the 

 latter suggested by PORCHER and HERVIEUX 4 ). With OBERMAYER'S 

 reagent the test is performed as follows : 



The acid urine (if alkaline it must be acidified with acetic acid) (ELLIN- 

 GER) is precipitated with basic lead acetate, 1 cc. for every 10 cc. of 

 the urine. 20 cc. of the filtrate are treated in a test-tube with an equal 

 volume of pure concentrated hydrochloric acid (specific gravity 1.19) 

 which contains 2-4 grams ferric chloride to the liter, and 2-3 cc. chloro- 

 form are added and the mixture immediately thoroughly shaken. The 

 chloroform is thereby colored more or less blue, depending upon the 

 amount of indican. Besides indigo blue we may also have indigo red 

 produced, whose formation has been explained in various ways. The 



1 The work of Porcher and Hervieux can be found in Compt. Rend., 145, Compt. 

 rend. soc. biol., 62, and Bull. soc. chim. (4), 1; Benedicenti, Zeitschr. f. physiol. Chem., 

 53 and Arch. f. exp. Path. u. Pharm., 1908, Suppl. (Schmiedeberg's Festschr.). 



2 See Jaff, Pfluger's Arch., 3; Senator, Centralbl. f. d. med. Wissensch., 1877; 

 G. Hoppe-Seyler, Zeitschr. f. physiol. Chem., 12 (contains older literature; also Berl., 

 klin. Wochenschr., 1892. 



3 Baumann with Brieger, Zeitschr. f. physiol. Chem., 3; with Thesen, ibid., 23. 



4 Jaffe, Pfluger's Arch., 3; Obermeyer, Wien. klin. Wochenschr., 1890; Salkowski, 

 Zeitschr. f. physiol. Chem., 67; Porcher and Hervieux, Zeitschr. f. physiol. Chem., 39. 



