86 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



also given by cholic acid (cholalic acid), a cleavage product 

 of both bile-acids. 



Pettenkofer's Test for the Bile-acids. 



Use either a 1 per cent, solution of the crystallized salts 

 of the bile-acids or of the commercial fel tauri depurat. sice. 



Add to a few cubic centimeters hi a test-tube five drops of 

 a 10 per cent, solution of cane-sugar (or add a small piece of 

 cane-sugar and dissolve this by shaking) . Then let about half 

 the volume of concentrated sulphuric acid flow slowly down 

 the side of the tube, held in a slanting position, so that the sul- 

 phuric acid forms the under layer. At the surface of contact of 

 the two liquids a purple-violet color appears. Dip the test- 

 tube into a cylinder or beaker filled with water and mix the 

 sulphuric acid and the solution of the bile-acid's, but not too 

 quickly, 1 by moving the test-tube around the walls of the 

 vessel in circles; a deep purple solution results. For exam- 

 ination with the spectroscope pour a little of the solution 

 into a few cubic centimeters of glacial acetic acid and about 

 the same amount into some alcohol. 



(a) The acetic acid solution shows an absorption-band in 

 the green and a more or less pronounced greenish fluorescence. 



(6) The alcoholic solution also shows immediately after 

 mixing only this one band, but very soon it takes on a brown- 

 ish shade and then shows two pronounced absorption-bands 

 in the green and in the blue. 



Modification of the Test according to Mylius. 2 



Instead of the cane-sugar use a drop of furfurol solution 

 (a drop of furfurol shaken thoroughly in a test-tube with 

 10 c.c. of water). The reaction develops more slowly, 



1 If the temperature exceeds 70 during the mixing the pigment is 

 destroyed. 



2 Zeit. fur physiol. Chemie, 11, 493. 



