122 CARBOHYDRATES. 



the same way as the Biuret reaction for Proteids. In 

 the latter, however, there is no boiling.) 



Perform a control test with water. The hydrated 

 oxide is not redissolved. 



2. Fehling's solution. Take 4 cm , boil it, then pour down the 



side of the sloped tube a few drops of the sugar solution. 

 If enough sugar is present an orange top stratum of 

 suboxide will form in a few moments. If not heat again. 

 Take 1 crn of the reduced fluid and add NH 3 until it 

 is redissolved. Note the volumes required to do so (Pavy). 



3. Add one-quarter volume saturated solution Picric Acid to 4 cm 



of the fluid, and then a few drops NaOH. Heat = a rich 

 red port colour results. 



4. Moore's test. To 2 cm of the fluid add an equal quantity of 



NaOH solution, boil = a yellow to deep brown colour 

 results, depending upon the amount of sugar present. 

 There is an odour of caramel, especially on adding weak 

 H a SO 4 . 



5. Phenyl-hydrazin test. To a tube three-quarters full of the 



solution add one knife-point of phenyl-hydrazin and one 

 of sodium acetate. Boil in the water-bath for thirty minutes 

 or more. On cooling, or before, a yellow crystalline or 

 amorphous pp of phenyl-glucosazone separates. Crystals 

 fine yellow needles in feathery clusters. Examine them 

 under the microscope (//). 



6. Barfoeds Reagent. Performed in the same way as Fehling's 



test = reduction. Herein differs from milk sugar, maltose 

 and dextrin, which do not reduce this reagent. 



7. Fermentation test with yeast, see abnormal urine later. 



