CHEMIC COMPOSITION OF THE HUMAN BODY. II 



compounds and especially to alcohol and carbon dioxid. The change is 

 expressed in the following equation: 



Dextrose. Alcohol. Carbon 

 Dioxid. 



About ninety-five per cent, of the dextrose is so changed, the remaining 

 five per cent, yielding secondary products succinic acid, glycerin, etc. 



Levulose, or fruit-sugar, is found in association with dextrose as a 

 constituent of many fruits. It is sweeter than dextrose and more soluble 

 in both water and dilute alcohol. From alcoholic solutions it crystallizes 

 in fine, silky needles, though it usually occurs in the form of a syrup. 



Levulose is distinguished from dextrose by its property of turning the 

 plane of polarized light to the left; the extent to which it does so, however, 

 varies with the temperature and concentration of the solution. 



Under the influence of the yeast plant it slowly undergoes fermentation, 

 yielding the same products as dextrose. It also has a reducing action on 

 cupric oxid. 



Galactose is obtained by boiling milk-sugar (lactose) with dilute sulphuric 

 acid. In many chemic relations it resembles dextrose. It is less soluble in 

 water, however, crystallizes more easily, and has a greater dextro-rotary 

 power. It also undergoes fermentation with the yeast plant. 



3. SACCHAROSES, C 12 H 22 O U . 



Saccharose, or cane-sugar, is widely distributed throughout the vege- 

 table world, but is especially abundant in sugar-cane, sorghum cane, sugar- 

 beet, Indian corn, etc. It crystallizes in large monoclinic prisms. It is 

 soluble in water and in dilute alcohol. Saccharos has no reducing power 

 on cupric oxid, and hence its presence cannot be detected by Fehling's 

 solution. It is dextro-rotary. Boiled with dilute mineral, as well as organic 

 acids, saccharose combines with water, and undergoes some change in 

 virtue of which it rotates the plane of polarized light to the left, and hence 

 the product is termed invert sugar. This latter has been shown to be a 

 mixture of equal quantities of levulose and dextrose. This inversion of 

 saccharose through hydration and decomposition is expressed by the follow- 

 ing equation: 



C tt H H li +H i O^C.H u O.+C.H rt 4 . 



Saccharose. Water. Levulose. Dextrose. 



Invert Sugar. 



Saccharose is not directly fermentable by yeast, but through the specific 

 action of a ferment, invertin or invertase, secreted by the yeast plant, or the 



