'58 



PHYSIOLOGICAL CHEMISTRY. 



7. Analysis of Biliary Calculi. Grind the calculus in a mortar 

 with 10 c.c. of ether. Filter. 



Filtrate I. 



I 



Allow to evaporate and examine 

 for cholesterol crystals (Fig. 42, 

 P- JSP)- (For further tests see ex- 

 periment 8, below.) 



Residue I. 



(On paper and in mortar.) 



Treat with dilute hydrochloric 

 acid and filter. 



Filtrate II. 



Test for calcium, phos- 

 phates and iron. Evapo- 

 rate remainder of filtrate 

 to dryness in porcelain 

 crucible and ignite. Dis- 

 solve residue in dilute 

 hydrochloric acid and 

 make alkaline with am- 

 monium hydroxide. Blue 

 color indicates copper. 



Residue II. 



(On paper and in mortar.) 



Dry the filter 



Wash with a little water, 

 paper. I 



Treat with 5 c.c. chloroform and filter. 



Filtrate III. 



Bilirubin. 



(Apply test for bile 

 pigments.) 



Residue III. 

 (On paper and in 

 mortar.) I 



Treat with 5 c.c. of 

 hot alcohol. 



Biliverdin. 

 8. Tests for Cholesterol. 



(a) Microscopical Examination. Examine the crystals under 

 the microscope and compare them with those shown in Fig. 42, page 



159- 



(&) Iodine-Sulphuric Acid Test. Place a few crystals of choles- 

 terol in one of the depressions of a test-tablet and treat with a drop 

 of concentrated sulphuric acid and a drop of a very dilute solution 

 of iodine. A play of colors consisting of violet, blue, green and red 

 results. 



(c) The Liebermann-Bur chard Test. Dissolve a few crystals of 

 cholesterol in 2 c.c. of chloroform in a dry test-tube. Now add 10 

 drops of acetic anhydride and 1-3 drops of concentrated sulphuric 

 acid. The solution becomes red, then blue, and finally bluish- 

 green in color. 



(d) Salkowski's Test. Dissolve a few crystals of cholesterol in 

 a little chloroform and add an equal volume of concentrated sul- 

 phuric acicl. A play of colors from bluish-red to cherry-red and 



