Dextrose

Dextrose (Glucose, or Grape-Sugar) is a member of the group of carbohydrates (q.v.) termed hexoses - i.e. those containing six atoms of carbon in the molecule. It is found in honey and many fruits, and in small quantities in the blood and urine. In the disease diabetes the quantity present in the urine increases greatly, and may reach 10 per cent. It is formed, together with another sugar, levulose (q.v.), by boiling cane-sugar with acids, and also by the similar treatment of starch, or cellulose, which are the substances chiefly employed for its manufacture on the large scale. It may be obtained similarly, together with other products, from a class of bodies known as glucosides (q.v.). It is soluble in water, and is sweet to the taste, though not as sweet as cane-sugar. As ordinarily obtained it is dextro-rotatory, but it has recently been shown that an equally active, laevo-rotatory, as well as inactive dextrose exists. Its composition is represented by the formula C₆H₁₂O₆, and it appears to be an aldehyde (q.v.), having a constitution CH₂OH . (CHOH)₄ . CHO. It has recently been artificially prepared, and its relations with other sugars shown. It undergoes fermentation by the action of yeast, with the production of alcohol and carbon-dioxide :

C₆H₁₂O₂ = 2C₂H₆O + 2CO₂

For its quantitative estimation it is added to a definite quantity of a boiling standard solution known as Fehling's solution (q.v.) until the blue colour which this reagent possesses is completely discharged. It is also estimated by means of a form of polarimeter (q.v.) known as a saccharimeter (q.v.).