534 CONSIDERATION OF CARBON COMPOUNDS. 



energetically upon cane-sugar, which is a strong reducing agent. A 

 mixture of cane-sugar and potassium chlorate will deflagrate when 

 moistened with sulphuric acid ; potassium permanganate is readily 

 deoxidized in acid solution ; cane-sugar, however, does not affect an 

 alkaline copper solution, and does not itself ferment ; but when heated 

 with dilute acids or left in contact with yeast in the presence of vari- 

 ous bacteria it is decomposed into dextrose and levulose, both of which 

 are fermentable. Like dextrose, cane-sugar forms compounds with met- 

 als, metallic oxides, and salts, which compounds are known as sucrates. 



Experiment 64 Make a one per cent, cane-sugar solution ; test it with 

 Fehling's solution and notice that no cuprous oxide is precipitated. Add to 

 50 c c. of the cane-sugar solution 5 drops of hydrochloric acid and heat on a 

 water-bath for half an hour. Again examine the liquid with Fehling's solu- 

 tion ; a precipitate of cuprous oxide is now formed, proving the conversion of 

 cane-sugar into dextrose (grape-sugar) and levulose. 



Maltose, C 12 H 22 O n , is obtained by the action of diastase on starch. 

 Diastase is a substance formed during the germination of various 

 seeds (rye, wheat, barley, etc.), and it is for this reason that grain 

 used for alcoholic liquors is converted into malt i. e., is allowed to 

 germinate, during which process diastase is formed, which, acting 

 upon the starch present, converts it into maltose and dextrin : 



3(C 6 H 10 5 ) + H 2 = C 12 H 22 U + C 6 H 10 6 . 

 Starch. Maltose. Dextrin. 



Maltose is also formed by the action of dilute sulphuric acid upon 

 starch, and is hence often present in commercial glucose ; by further 

 treatment with sulphuric acid it is converted into dextrose. Maltose 

 crystallizes, reduces alkaline copper solutions, and ferments with 

 yeast. 



Melitose, C 12 H 22 O n , is the chief constituent of Australian manna. 



Sugar of milk, Saccharum lactis, C 12 H 22 O n + H 2 O = 357.48 

 (Lactose). Found almost exclusively in the milk of the mammalia. 

 Obtained by freeing milk from casein and fat and evaporating the 

 remaining liquid (whey) to a small bulk, when the milk-sugar crys- 

 tallizes on cooling. 



It forms white, hard, crystalline masses ; it is soluble in about 6 

 parts of water (at 15 C., 59 F.) and in 1 part of boiling water, 

 insoluble in alcohol and ether; it is much harder than cane-sugar, 

 and but faintly sweet; it is not easily brought into alcoholic fermen- 

 tation by the action of yeast, but easily undergoes " lactic fermenta- 

 tion" when cheese is added. During this process milk-sugar is 



