6 LABORATORY WORK IN PHYSIOLOGICAL CHEMISTRY. 



of water and break down into two molecules of a monosac- 

 charide. 



This decomposition in the case of saccharose has assumed 

 the name of inversion from the fact that when a dextro- 

 rotatory solution of cane-sugar suffers hydrolysis, the result- 

 ant mixture is Isevogyrate. This is caused by the strong 

 laevo-rotation of the Isevulose more than overcoming the 

 dextrogyrate polarization of the dextrose. 



Saccharose = dextrose +lsevulose. 

 SACCHAROSE = CANE-SUGAR = SUCROSE. 



Sa3charose differs from the other members of this group 

 in not reducing metallic oxides in alkaline solution and in 

 not forming osazones with phenylhyclrazin. It is not 

 directly fermentable with yeast, but only after previous 

 inversion by the ferment invertin, secreted by the yeast-cell. 

 A slight reduction which is sometimes obtainable with 

 Fehling's test may be explained by the inverting action of 

 the strong alkali. 



Use a 1 per cent solution of cane-sugar. 



Tests: (a) Fehling's; Moore's; Nylander's; Barfoed's; 

 using in each case 5 c.c. of the saccharose solution. Com- 

 pare these results with those obtained for dextrose. 



(6) To 10 c.c. of the saccharose solution add 1 c.c. concen- 

 trated HC1 and boil several minutes. Allow this to cool 

 and then neutralize with NaOH. Use this solution in making 

 Fehling's, Nylander's, and Barfoed's tests. Write the equa- 

 tions for the chemical changes which have taken place and 

 determine the character of the carbohydrate formed. 



Inversion and Fermentation. 



1. Examine the saccharose solution in the polariscope 

 and determine the degree of rotation. 



