82 HANDBOOK FOR BIO-CHEMICAL LABORATORY, 



and alkali, but this turns yellow, and then gradually green 

 and blue, when saturated with acetic acid. Ammonia may 

 be substituted for the caustic soda or potash and gives the 

 same reaction with acetone, but no reaction with creatinin. 



LE NOBEL'S Modification of LEGAL'S Test (Acetone). 

 Instead of using caustic potash or soda with the sodium nitro- 

 prusside he suggests the use of ammonia, which produces a 

 ruby-red reaction with acetone, but not with creatinin. (See 

 Legal's Test.) 



LE NOBEL'S Test (Bile Pigments). Treat the liquid with 

 zinc chloride and a few drops of tincture of iodine. A di- 

 chroitic play of colors is the result. 



LEUCIN. See Hoffmeister, Scherer. 



LIEBEN'S Test (Acetone). When a watery solution of 

 acetone is treated with alkali and then a solution of iodine in 

 potassium iodide solution and gently warmed, a yellow pre- 

 cipitate of iodoforrn is formed, which is known by its odor and 

 by the appearance of the crystals (six-sided plates or stars) 

 under the microscope. 



LiEBERMAN^-BuRCHARD's Test (Cholesterin). Dissolve 

 the substance in acetic anhydride and then add concentrated 

 sulphuric acid, when a beautiful violet color is produced, and 

 this passes quickly to green if cholesterin is present. 



LIEBERMAN^S Test (Proteids). Treat the proteid, pre- 

 viously washed with alcohol and ether, with concentrated 

 fuming hydrochloric acid, when a beautiful violet-blue colora- 

 tion is the result. This liquid gives an absorption-band be- 

 tween E and b. 



LIEBIG ? S Test (Cystin). Boil the substance with caujtic 

 alkali containing lead oxide. If cystin is present, a pre- 

 cipitate of black lead sulphide is produced. 



