62 



Bile pigments. The urine has usually a yellow or yellow- 

 ish green color and froths easily when shaken. Filter paper 

 dipped into it gives a yellow stain on drying. 



281. Gmelin's test (nitric acid containing nitrous acid). 

 Place a few drops of the suspected urine in a white porce- 

 lain dish and near it a few drops of the impure nitric acid, 

 and let the fluids run together and the usual play of colors 

 is observed. 



282. Take urine in a test-tube pour in the impure nitric 

 acid until it forms a stratum at the bottom. If the bile pig- 

 ments be present, at the line of junction of the fluids, a play 

 of colors takes place — from above downwards — green, blue, 

 violet or dirty red, and yellow. Nearly all urines give a 

 play of colors, but green is the necessary and characteristic 

 color to prove the presence of bile pigments. 



283. Ro.senbach's modification. Filter the urine several 

 times through the same filter, dry the filter paper and to it 

 apply the impure nitric acid, when the same play of colors 

 is observed. 



284. A solution of methyl violet poured on the urine by 

 the contact method, gives a bright carmine ring at the point 

 of contact. 



285. Mix I cc. of urine with 2 cc. of ether and then agi- 

 tate with five drops of tincture of iodine. After standing, 

 the ether, holding in solution the iodine, will form the upper 

 layer, while the urine beneath takes on a brilliant green 

 coloration if biliverdin is pre.sent. 



286. Bile Acids. (Glycocholic and Taurocholic acids). 

 Pettenkofer's test. Add to the urine a few drops of syrup 

 of cane sugar (10%), mix them, and pour strong sulphuric 

 acid down the side of the tube until it forms a layer at the 

 bottom. The temperature must not rise above 70° C. nor 

 must the urine contain albumin. At the line of junction a 

 cherry red or purple violet color indicates the presence of 

 bile acids. Another method is to shake the urine and syrup 



