Il8 ORGANIC AGRICULTURAL CHEMISTRY 



readily crystallized fructose, but the crystallization is difficult 

 and it is not a practical method for obtaining glucose. Invert 

 sugar occurs in honey together with sucrose. As both glucose 

 and fructose reduce Fehling's solution, invert sugar also re- 

 duces it and in a definite amount. The determination of the 

 amount of sucrose in a solution by inverting it and then deter- 

 mining by Fehling's solution the amount of invert sugar present 

 is a practical laboratory method of analysis. As sucrose is 

 dextro-rotatory and invert sugar is levo-rotatory the deter- 

 mination of the optical rotation both before and after inver- 

 sion gives a second practical method for determining the amounts 

 of sucrose and invert sugar present in a mixture of the two sub- 

 stances. 



Sugar Analysis. — This is in brief the principle of methods of 

 analysis of all sugar-containing liquids such as are dealt with 

 in all sugar-producing and refining processes, or in the study 

 of plant constituents. Details of methods will be found in books 

 on analytical chemistry or sugar analysis. 



Maltose, Malt Sugar, C12H22O11 



Maltose or malt sugar is the second of the important di- 

 saccharoses. It is present in malted grain, or malt, where it is 

 produced from starch. When malt is extracted with water 

 and the extract evaporated, a sirup is obtained containing 

 maltose in solution. From such solution maltose may be ob- 

 tained as a crystalline substance. It forms needle crystals 

 with one molecule of water. It is easily soluble in water, and 

 only slightly so in alcohol. It reduces Fehling^s solution, but 

 is not fermentable by zymase. It is optically active, being dextro- 

 rotatory. After hydrolysis to a monosaccharose, as in the case 

 of cane sugar, the product is fermentable. When hydrolyzed 

 by enzymes or by boiling with acids, two molecules of glucose are 

 obtained. This reaction is not accompanied with optical in- 

 version as in the case of cane sugar, as both the maltose and the 

 hydrolytic product, glucose, are dextro-rotatory. 



