92 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



acid, and shake thoroughly several times. The chloroform 

 solution turns blood-red, gradually changes to cherry-red, 

 and finally to purple. The sulphuric acid under the chloro- 

 form solution shows a greenish fluorescence. If now some of 

 the chloroform solution is poured into a wet test-tube and 

 shaken, it will quickly become colorless, and upon adding 

 sulphuric acid the original red color will be restored. When 

 poured out into a dish the chloroform will also become color- 

 less from the moisture which it abstracts from the air. If 

 the purple-colored chloroform solution is diluted by the addi- 

 tion of more chloroform, it often turns blue (in consequence 

 of a small amount of water in the chloroform), and the addi- 

 tion of sulphuric acid turns it red again. In very dilute 

 solutions (a trace of cholesterin dissolved in chloroform) the 

 reaction is somewhat different, but also characteristic: yel- 

 low to rose color of the chloroform, yellow color of the sul- 

 phuric acid with a greenish fluorescence. 



3. Liebermann-Burchard Reaction. Dissolve a small quan- 

 tity of the cholesterin in a few cubic centimeters of chloroform 

 in a dry test-tube, add two or three drops of acetic anhydride, 

 and then concentrated sulphuric acid, drop by drop. A rose 

 color first develops, then a beautiful blue, which finally turns 

 bluish green. If only a very small quantity of cholesterin 

 is used, the green color develops after standing a few min- 

 utes. 



Both tests, 2 and 3, are equally delicate. Not only cho- 

 lesterin but also its esters, such as those of palmitic and 

 stearic acid occurring in nature (Liebreich's lanolin), give 

 the reactions. 



If a somewhat larger quantity of cholesterin is available, 

 purify it by repeated recrystallization from hot absolute 

 alcohol, press the crystals between filter-paper, and deter- 

 mine the melting-point. It melts at 145 (distinction from 

 the cholesterin occurring in plants, phytosterin, which gives 



