260 PHYSIOLOGICAL CHEMISTRY 



II. Disaccharides 



Saccharose (Sucrose). Study the properties of saccharose 

 as follows : 



19. Solubility. (See note on solubility determinations under 

 Dextrose). Test the solubility of cane sugar in water, cold alco- 

 hol, hot alcohol (do not warm over a flame, dip the test tube 

 in hot water) and ether. 



20. Try Benedict's Test. Saccharose does not reduce Bene- 

 dict's solution on short boiling since it has no free aldehyde or 

 ketoiie group. Try boiling for several minutes. On prolonged 

 boiling some reduction takes place. 



21. Phenylhydrazine. Cane sugar forms no osazone. 



22. Inversion of Saccharose. By boiling with dilute acids sac- 

 charose may be broken up into dextrose and levulose. After 

 ascertaining that the saccharose solution will not reduce Bene- 

 dict 's, take another sample of saccharose solution, acidify slightly 

 by adding about 1 c.c. of dilute sulphuric acid and heat on the 

 water bath for 15 minutes. Test again with Benedict's solution. 

 The saccharose will have been hydrolyzed into dextrose and 

 levulose, and the liquid should reduce Benedict's solution. 



23. Optical Activity Before and After Inversion. Determine 

 the rotation of the solution of saccharose. Determine the rota- 

 tion of a portion of the same solution which has been inverted. 

 The rotation should now be to the left, since the solution contains 

 equal amounts of dextrose and levulose, and the latter is stronger 

 levorotatory than the former is dextrorotatory. 



24. Perform a Fermentation Test with Saccharose. 



Maltose. Repeat the following tests performed on sac- 

 charose, using a maltose solution : 



25. Solubility in water, alcohol and ether. 



26. Benedict's. 



27. Phenylhydrazine. 



28. Fermentation. 



