The Juilliard's program at the Library of Congress last night was an odd mix of the humorless and the slapstick with a little wry sophistication thrown in.

The latter was provided by the opening Ravel Sonata for Violin and Cello, where spirited conversation between the instruments alternated with laid-back monologues. Robert Mann and Joel Krosnick got off to a pedestrian beginning but warmed up quickly to more imaginative music-making.

The full quartet gave the Hindemith Quartet No. 3 the sort of serious intensity it requires. These days, parts of the piece come across as contrived exercises in formal structures, but it has its moments of charm. The third movement, in particular, with a lyrical dimension that the rest lacked, was like an oasis in an otherwise rigid landscape. Playing with restraint and care, the Juilliard gave it a well-paced and nicely balanced reading.

Mozart's late quartet in F major, K. 590, has moments of almost Gilbert and Sullivan silliness. The last movement dashes about from pillar to post with marvelously heedless wantonness, but it is perhaps not supposed to convey quite the free-for-all air the Juilliard imparted to it. As a foil for the rest of the program, it worked pretty well, but more elegant treatment might have served the program as well and Mozart somewhat better.