Fehling's solution

9.5

A blue liquid used in labs to test for sugar that turns reddish-orange when sugar is present

noun
/ˈfeɪlɪŋz səˈluːʃən/

Specialized

: solución de Fehling

When glucose is present, Fehling's solution changes color from blue to reddish-orange.

Examples

The doctor added Fehling's solution to the test tube to check the patient's urine for sugar.
In the laboratory, students learned how to use Fehling's solution to detect reducing sugars.
We used Fehling's solution to test for glucose in the sample.
Have you prepared Fehling's solution for the experiment?
In the laboratory, students learned how to use Fehling's solution to detect reducing sugars.
When glucose is present, Fehling's solution changes color from blue to reddish-orange.
We used Fehling's solution to test for glucose in the sample.

Surface Forms

Fehling's solution singular

Fehling's solutions plural

Morphology

Fehling's + solution

This is an eponymous technical term: knowing 'solution' only gives the general idea of a liquid mixture, while 'Fehling's' is a proper name that does not convey the chemical composition or its use. A B1 learner who knows the constituents would not be able to infer that it is a specific reagent for testing reducing sugars, so the meaning is not derivable from the parts.

Etymology

Fehling's solution is named after the chemist Wilhelm Fehling, who made a blue liquid that turns reddish-orange when it meets certain sugars. That clear image — a blue solution changing colour — explains why Fehling's solution is used 'to test for sugar'.