1. 1,2-Bis(b-tolvlamino)ethane has been found to be a more satisfactory and specific reagent for the characterization of aldehydes than 1,2-bis(benzylamino)ethane,1, 2-bis(p-methoxybenzylamino)ethane or 1,2-bis(p-chlorobenzylamino)ethane. It has also been found that the reaction between the reagent and acetone, acetophenone and some aldoses and ketoses is not noticeable.