350 CONSIDERATION OF CARBON COMPOUNDS. 



identical in composition with grape-sugar, inosite differs from the 

 latter in not being fermentable and by not precipitating cuprous 

 oxide from alkaline copper-solutions. 



Cane-sugar, Saccharum, C 12 H 22 O U = 342 (Ordinary saccharose, 

 Common sugar, Beet-sugar). Cane-sugar is found in the juices of 

 many plants, especially in that of the different grasses (sugar-cane), 

 and also in the sap of several forest trees (maple), in the roots, stems, 

 and other parts of various plants (sugar-beet), etc. Plants contain- 

 ing cane-sugar do not contain free organic acids, which latter would 

 convert it into grape-sugar. 



Cane-sugar is manufactured from various plants containing it by 

 crushing them between rollers, expressing the juice, heating and 

 adding to it milk of lime, which precipitates vegetable albuminous 

 matter. The clear liquid is evaporated to the consistency of a syrup, 

 which is further purified (refined) by filtering it through bone-black 

 and evaporating the solution in " vacuum pans" to the crystallizing- 

 point; the mother-liquors are further evaporated, and yield lower 

 grades of sugar ; finally a syrup is left which is known as molasses. 



Cane-sugar forms white, hard, distinctly crystalline granules, but 

 may be obtained also in well-formed, large, monocliuic prisms. It 

 dissolves in 0.2 part of boiling, in 0.5 part of cold water, and in 175 

 parts of alcohol ; when heated to 160 C. (320 F.) it fuses, and the 

 liquid, on cooling, forms an amorphous, transparent mass, known as 

 barley sugar; at a higher temperature cane sugar is decomposed, 

 water is evolved, and a brown, almost tasteless substance is formed, 

 which is known as caramel or burnt sugar. Oxidizing agents act 

 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 ferment itself; but when heated 

 with dilute acids or left in contact with yeast for some time, it is 

 decomposed into dextrose and levulose, both of which are ferment- 

 able. Like dextrose, cane-sugar forms compounds with metals, 

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



Experiment 53. 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 glucose. 



