Brünnhilde made a guest appearance Friday night in the middle of J.S. Bach's joyous Cantata No. 51 (``Jauchzet Gott!"), a piece usually sung by lyric sopranos of the Kathleen Battle mold. On the word ``Alleluja," a remarkable high C came out of the mouth of Barbara Quintiliani and, parting audience members' hair on the way, blazed out of Faneuil Hall into the night sky.
Quintiliani, the Quincy native who is making good on regional opera stages, was the guest soloist in an all-Baroque concert by the Boston Classical Orchestra and the Boston Cecilia chorus, led by Steven Lipsitt. The unusual program included two of Bach's solo cantatas (the other was No. 202) and four choruses of praise, plus Handel's Royal Fireworks Music and the finale from his ``Ode to St. Cecilia's Day." It was almost too much of a good thing, but not quite.