Measure about 15 mL of hydrated copper sulfate solution in a measuring cylinder and pour the solution into the 180 mL beaker. Rinse the measuring cylinder with distilled water and pour 15 mL of the potassium nitrate tartrate into it. Pour this solution into the beaker holding the copper sulfate solution. Stir with a stirring rod to form a homogenous mixture of Fehling's solution.
Rinse the measuring cylinder with distilled water and measure 25 mL of solution labeled A. Pour the solution into one of the boiling tubes. Rinse the measuring cylinder again. Measure 25 mL of solution labeled B and pour it onto the second boiling tube. Rinse again and perform the same procedure adding the solution labeled C to the third boiling tube.
Place the boiling tubes with the solutions A, B and C on the three test-tube holders. Use a dropper to add three to four drops of the Fehling's solution to each boiling tube containing the carbohydrate solutions. Place the boiling tubes simultaneously above a Bunsen burner and boil. Shake the boiling tubes continuously to minimize
spitting.
Observe the changes. A brick-red color formation in the solutions and a greenish suspension indicate the presence of simple sugars. No color change in the solutions means no simple sugars are present.