ORGANIC COMPOUNDS OF PLANTS 189 



pans. In the presence of all acids, even dilute organic 

 acids, hydrolysis or inversion of sucrose takes place. 



245. Milk-Sugar (lactose) is found in cow's milk to 

 the extent of 4.5 to 5 per cent., and is present in the 

 milk of all mammals. It has the same general but a dif- 

 ferent structural composition from sucrose. 



246. flaltose is a sugar produced in the malting of 

 barley and other grains by the action of ferments upon 

 starch, the reaction being 



2 C 6 H 12 6 - H 2 + C 12 H 22 O n . 



Maltose is not found to any extent in plant bodies, but is 

 present in prepared foods which have undergone the malt- 

 ing process. 



247. Inversion of Sucrose. When sucrose is acted 

 upon by heat and dilute acids, as well as other chemicals, 

 inversion takes place. One molecule of water is chemi- 

 cally united to one molecule of sucrose which splits up 

 and forms the two sugars, levulose and dextrose. 



Sucrose. I<evulose. Dextrose. 



C 12 H 22 O n + H 2 = C 6 H 12 6 + C 6 H 12 6 . 

 This process takes place in the ripening of fruits and in 

 the curing of many fodders, as well as in the cooking and 

 preparation of human foods. 



Experiment 48. Inversion of cane-sugar. Place 2 grams 

 sugar, 30 cc. H 2 O, and 2 cc. H 2 SO^ in an evaporator. Heat 

 fifteen minutes on a sand-bath, replacing the water lost by 

 evaporation. Neutralize with CaCO 3 and filter, adding more 

 water if necessary for filtration. Test 5 cc. of the filtrate with 

 an alkaline solution of copper sulfate (Fehling's solution) 

 as directed in Experiment 34. Take o.i gram of sugar, dis- 



