A positive carbylamine test is given by

Primary amines provide the carbbylamine test.
Therefore, the carbylamine test will result in positive results for 2,4-dimethyl aniline and p-methyl benzylamine.
The two amines' structures are displayed above.

A positive carbylamine test occurs when a primary or secondary amine reacts with an aldehyde or ketone in the presence of a strong base, usually potassium hydroxide (KOH), forming an isocyanide (also called carbylamine). The reaction is characterized by the formation of a foul-smelling, yellow, or reddish-brown precipitate. This test is used to distinguish amines from other organic compounds, as it specifically indicates the presence of amines. The test works because amines can react with carbonyl compounds to form these distinctive, smelly isocyanides.