S found to be 9.2. Inversion by hydrochloric acid gave /= 16.5; 

 by invertase /= 9.7. The percentage of cane sugar determined by 

 acid inversion was 5.5; by invertase inversion, 0.4. This analysis 

 shows such a striking disagreement between the two methods that a 

 further determination of the reducing sugar before and after the 

 hydrolyses was made with Fehling's solution. The true carbohydrate 

 composition of this plant was found by this method to be: 



s Per cent. 



Reducing sugars 2. 8 



Cane sugar (by invertase inversion) 0. 7 



Unknown carbohydrate (by acid inversion) 13. 3 



Here, then, is a substance which contains only a trace of cane sugar, 

 but a large quantity of a very easily hydrolyzed carbohydrate; further 

 work on the nature of this unknown carbohydrate is in progress. 



5. Test on commercial glucose. A 26 per cent solution of "mixing 

 glucose," which is prepared by the acid hydrolysis of starch, gave a 

 rotation of 86.0 V. Inversion by hot hydrochloric acid changed this 

 to 85.2, by cold acid, 85.3. Five drops of invertase solution were 

 added to a third portion and after standing overnight its rotation was 

 still 86.0. The method of manufacture of this mixing glucose by hot 

 acid hydrolysis makes it certain that no cane sugar can be present in 

 it, and the method of analysis in which invertase is employed shows 

 no cane sugar, but the usual acid methods give a slight decrease of 

 rotation. Weber and McPherson a have particularly investigated this 

 error in the acid methods of hydrolysis and devised a correction for 

 it, but the invertase method is certainly preferable. 



6. Commercial glucose with added cane sugar. Commercial glucose 

 is frequently .flavored with a small quantity of cane sirup to make it 

 more palatable, and it is then sold for table use. A determination of 

 cane sugar in such "cane-flavored" glucose gave the following: Rota- 

 tion of a 13 per cent solution of the sample in a 200-mm tube 75.0 V; 

 rotation after inversion with hot hydrochloric acid, 72.7; with cold 

 hydrochloric acid, 73.8; inversion by invertase, 74.0. These results 

 show that the acid methods indicate more cane sugar than does the 

 invertase hydrolysis, and there is no question but that the invertase 

 determination is more nearly correct. 



THE HYDROLYSIS OF BAFFINOSE BY INVEBTASE. 



The peculiar trisaccharid sugar raflSnose, which occurs in cotton- 

 seed, in wheat, and in the sugar beet, is hydrolyzed by invertase, and 

 the method for estimating cane sugar by inversion with invertase is 

 accordingly not applicable in case raifinose is present. Raffinose is 

 also hydrolyzed by hydrochloric acid, and therefore the acid bydro- 



a J. Amer. Chem. Soc., 1895, 17 : 312-320. 

 Cir. 50. 



