Legal's Test for Acetone
Historical document, translated for reference. It reflects medical knowledge of the 1920s–30s and is not medical advice.
Summary
Legal's test is a chemical reaction used to detect acetone in a solution using sodium nitroprusside and caustic alkali. The appearance of a ruby-red color indicates acetone, though creatinine causes a similar initial reaction that can be differentiated by adding excess acetic acid.
Encyclopedia entry (1928–1936)
LEGAL'S TEST (Legal) for acetone. A few drops of a freshly prepared solution of sodium nitroprusside Na2FeCy5(NO) and a little solution of caustic potash or soda are added to the test solution. If acetone is present, the liquid turns a ruby-red color; the same coloration is produced in the presence of creatinine. If an excess of acetic acid is then added, the coloration due to acetone changes to carmine or purple-red, and upon standing to violet or blue, whereas in the case of creatinine it turns yellow.
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Cite this page
“Legal's Test for Acetone.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.pages.dev/article/legals-test-for-acetone/