86 HANDBOOK FOR BIO-CHEMICAL LABORATORY. 



solution becomes first yellow, then orange, yellowish brown, 

 and lastly brown, depending upon the amount of glucose 

 present. A faint odor of caramel is also observed, and this 

 is more pronounced if the solution is acidified. 



MULDER'S Test (Glucose). Treat the solution with a solu- 

 tion of sodium carbonate and add a solution of indigo car- 

 mine. On heating in the presence of glucose the solution 

 becomes decolorized, and turns blue again on shaking with 

 air. 



MULDER'S Test, also Xantho-proteic Reaction (Proteids). 

 On treating proteids with concentrated nitric acid they are 

 colored yellow. On adding ammonia or cavstic soda or potash 

 they turn orange yellow. 



MULLER'S Test (Cystin). Dissolve the cystin by boiling 

 with caustic potash, dilute with water when cold, and add a 

 solution of sodium nitro-prusside, when a violet coloration is 

 produced. This color changes rapidly to yellow. 



MUREXID Test (Uric Acid). Heat the powder gently on a 

 watch-glass with a drop or two of strong nitric acid. A red 

 residue is produced, which, when cold, turns a purple red 

 when ammonia is added (purpurate of ammonium). When 

 caustic soda or potash is added to this, it becomes more blue 

 or bluish violet. Better results are obtained if the heating is 

 done over the water-bath, and not over a naked flame. 



MYLIUS'S Modification of Pettenkofer's Test (Bile Acids). 

 To each cubic centimetre of the alcoholic solution of bile 

 acids add 1 drop of furfurol solution and 1 c.c. concentrated 

 sulphuric acid, and cool when necessary, so that the test does 

 not become too warm. A red coloration is the result, and 

 this color does not disappear at the ordinary temperature, but 

 becomes more bluish violet in the course of a day. 



