Chemical Constituents of the Animal Body. 193 



Glucose or dextrose is found in large quantities in 

 grapes, hence the name " grape-sugar " is sometimes em- 

 ployed. It can be obtained by " inversion " of cane-sugar, 

 and is separated from the laevulose formed at the same time 

 by recrystallization from alcohol in which the latter sugar is 

 much more soluble. Lsevulose may also be separated from 

 invert sugar by the addition of slaked lime, with which, in 

 contradistinction to dextrose, it forms a compound which is 

 only slightly soluble in water. Dextrose can also be obtained 

 by the hydrolysis of starch. The knowledge of the con- 

 stitution of glucose is due chiefly to Kiliani, who showed 

 that it can be represented by the formula 



CH 2 OH 



CH(OH) 

 CH(OH) 

 CH(OH) 

 CH(OH) 



CH( 



[0 



Before the researches of Kiliani, it was known that five 

 alcoholic hydroxyl groups existed, as glucose on treat- 

 ment with acetyl chloride yielded a pentacetyl deriva- 

 tive. On reduction with nascent hydrogen, furthermore, 

 it was known . to yield a hexahydroxyl alcohol, which 

 on treatment with hydriodic acid yielded the normal 

 hexyl iodide, CH 3 - CH 2 CH 2 CH 2 CH 2 - CH 2 I. Kiliani 

 showed that dextrose, on treatment with hydrogen cyanide, 

 yielded a hydroxy nitrile (like other aldehydes), which on 

 hydrolysis formed a hexahydroxy heptylic acid. This 

 hydroxy acid, on treatment with hydriodic acid, gave rise 

 to normal heptylic acid. These changes can be repre- 

 sented by the formulse 



(1,997) 13 



