THE URINE. 367 



pnoma, fetid bronchitis, ichorous pleural exudations, diabetes 

 mellitus, and others. The increase of indican in the urine observed 

 in consumption and inanition depends probably upon the disturbed 

 digestion. In increased elimination of indican the elimination of 

 phenol is also increased ; a urine rich in phenol is, on the contrary, 

 not always rich in indican. 



The potassium-salt of indoxyl-sulphuric acid which was pre- 

 pared by BAUMANN and BRIEGER from the urine of a dog fed on 

 indol, crystallizes in colorless, shining plates or leaves which are 

 easily soluble in water but less readily in alcohol. It is split 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 : 

 2C 8 H 7 NO + 20 = C 16 H 10 N 2 2 -f 2H 8 0. 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, which also serve as an approximate 

 test for the quantity of indican, is sufficient. 



JAFFE'S Indican Test. 20 c. c. of urine are treated in a glass 

 with 2-3 c. c. chloroform and mixed with an equal volume of 

 concentrated hydrochloric acid. Immediately after a concentrated 

 chloride-of-lime solution or a \% potassium-permanganate solution is 

 added drop by drop, and after each drop the mixture is thoroughly 

 shaken. The chloroform is gradually colored faintly or strongly 

 blue. An excess of oxidizing reagent, especially chloride of lime, 

 interferes with the reaction and must therefore be avoided. The 

 test is repeated with somewhat varying amounts of oxidizing 

 material until a point is found at which the maximum coloration of 

 the chloroform takes place. From the intensity of the color the 

 quantity of indigo is determined. 



An exact determination of the amount of indigo in urine is very 

 rarely made. The methods suggested for this purpose are very 

 complicated, and even then they are not quite accurate; therefore 

 the reader is referred to other text-books for their description. 



Indol seems also to pass into the urine as a glycuronic acid, 

 indoxyl- gly cur onic acid (SCHMIEDEBERG). Such an acid has been 

 found in the urine of animals after the administration of the 

 sodium-salt of o-nitrophenylpropiolic acid (,G. HOPPE-SEYLER). 



