64 CHEMICAL PHYSIOLOGY. 



the fluid and dry the paper. On placing a drop of sulphuric 

 acid on the latter, after some time, a purple spot which has 

 eaten into the paper is observed. 



(/.) Repeat any or all of the above processes with a watery 

 solution of the bile salts. 



4. Similar colour reactions are obtained with many other sub- 

 stances e.g., albumin and fats. 



Albumin and Sulphuric Acid. To a solution of syntonin and 

 syrup add strong sulphuric acid, and a similar bint is obtained. 

 The spectra, however, are different, the red-purple fluid from bile 

 gives two absorption bands, one between E and F, and another 

 between D and E. In the albuminous solutions, only one 

 absorption band exists between E and F. 



5. Action of Bile or Bile-Salts in Precipitating Sulphur. 



(a.) Take two beakers and in one (A) place diluted bile, 

 and in the other (B) water. Pour flowers of sulphur on the 

 surface of the water of both. The sulphur falls in a copious 

 shower through the fluid of A, while none passes through B. 



(b.) Test to what extent bile may be diluted before it 

 loses this property, which is due to the diminution of the 

 surface tension by the bile-salts ( J/". Hay) . 



(c.) Perform the same experiment with a solution of the 

 bile-salts. 



Bile Pigments. The chief are bilimbin (red), biliverdin (green), 

 and urobilin. 



6. Gmelin's Test for the Bile Pigments. 



(a.) Place a few drops of bile on a white porcelain slab. 

 With a glass rod, place a drop or two of strong nitric acid 

 containing nitrous acid near the drop of bile, bring the acid 

 and bile into contact, when there is immediately a play of 

 colours, beginning with green and passing into blue, violet, 

 red, and dirty yellow. 



(b.) Place a little nitric acid in a test-tube. Slant the 

 tube and pour in bile, a similar play of colours occurs 



