406 PHYSIOLOGICAL CHEMISTRY. 



for GMELIN'S test (HoppE-SEYLER),and small amounts of bile-color- 

 ing matters may be detected in this way. The lime-pigments may, 

 according to HILGER, also be used directly for GMELIN'S test in the 

 following way : Spread them on a porcelain dish in a thin layer, 

 and add carefully a drop of nitric acid. The reaction generally 

 appears very beautiful. 



STOKVIS'S reaction is especially valuable in those cases in which 

 the urine contains only very little bile-coloring matter together with 

 larger amounts of other coloring matters. The test is performed 

 as follows : 20-30 c. c. urine are treated with 5-10 c. c. of a solu- 

 tion of zinc acetate (1 : 5). The precipitate is washed on a small 

 filter with water and then dissolved in a little ammonia. The new 

 filtrate gives, directly or after it has stood a short time in the air 

 until it has a peculiar brownish-green color, the absorption-bands 

 of bilicyanin (see page 155). 



Many other reactions for bile-coloring matters in the urine have 

 been proposed; but as the above-mentioned are sufficient, it is per- 

 haps only necessary to give here a few of the other reactions with- 

 out entering into details. 



ULTZMANN'S reaction consists in treating about 10 c. c. of the urine with 

 3-4 c. c. concentrated caustic-potash solution and then acidifying with hydro- 

 chloric acid. The urine will become a beautiful green. 



SMITH'S Reaction. Pour carefully over the urine tincture of iodine, whereby 

 a green ring appears between the two liquids. You may also shake the urine 

 with tincture of iodine until it has a green color. 



EHRLICH'S Test. First mix the urine with an equal volume of dilute acetic 

 acid and then add drop by drop a solution of sulpho-diazobenzol. The acid 

 mixture becomes dark red in the presence of bilirubin, and this color becomes 

 bluish violet on the addition of glacial acetic acid. The sulpho-diazobenzol 

 is prepared with 1 grm. sulphanilic acid, 15 c. c. hydrochloric acid, and* 0.1 

 grm. sodium nitrite ; this solution is diluted to 1 litre with water. 



MEDICINAL COLORING MATTERS produced from santonin, rhubarb, senua, 

 etc. , may give an abnormal color to the urine, which may be mistaken for the 

 bile-coloring matters, or in alkaline urines perhaps for blood-coloring matters. 

 If hydrochloric acid is added to such a urine, it becomes yellow or pale yellow, 

 while on the addition of an excess of alkali it becomes more or less beautifully 

 red. 



Sugar in Urine. 



Grape-sugar, C 6 H 12 6 , also called GLUCOSE, DEXTROSE, and 

 DIABETIC sugar, occurs chiefly in the vegetable kingdom; but it is 

 found in very small amounts in the blood, on an average of 1.5 p. m., 

 and also as traces in other animal fluids and organs. The occurrence 

 of traces of grape-sugar in the urine of perfectly healthy persons 

 can hardly be disputed. If sugar appears in the urine in constant 



