Johan Adolph Scheibe wrote at least three Triosonates for organ. The third of these triosonatas is the Triosonate in D major. It has three movements in the familiar order fast, slow, fast. Scheibe calls the first movement "Fuga" and he blends the form of fugue with the (in those days) emerging sonata form. In the exposition the fugue theme is played three times, one time in each voice. The development is based on the first three bars of the fugue and visits the keys of b minor and f sharp minor. After a few dense chromatic bars the fugue theme suddenly reappears in the bass voice. The recapitulation also features the fugue theme three times and ends with the same flourish as the exposition. The second movement is a melancholy piece, in which the two upper voices exchange motives and melodies, yet maintain their own individualality. It's not hard to imagine this piece beaing played by two separate instruments (a violin and a viola for example). The third movement is full of wit and energy, a fitting conclusion to the sonata.
Score available here: http://partitura.org/index.php/johann-adolph-scheibe-triosonate-d-dur