Ketones give positive results in Bradys test, the reaction with 2,4-dinitrophenylhydrazine to give the corresponding hydrazone. Ketones may be distinguished from aldehydes by giving a negative result with Tollens reagent or with Fehlings solution. Methyl ketones give positive results for the iodoform test. Ketones also give positive results when treated with m'-dinitrobenzene in presence of dilute sodium hydroxide to give violet coloration.