The last piece in the Leipziger manuscript with signature Becker II.2.51 is a prelude with a fugue. It has no named composer in the manuscript. However, based on the style of the piece I think it is save to presume Georg Wilhelm Saxer is the composer of this piece. The prelude is well written piece, with a strong motivic force, that is used through the entire piece. One could call it a Toccata, and with good reason. The fugue is like the other fugues by Saxer: very little musical development, just four expositions in a row, joined by very short episodic phrases. Like Wolfram Syré suggested, the overal effect is more like a concerto than a fugue. It is a great piece to play and (in my opinion) a great piece to listen to. Sadly, it's the last Saxer composition available in this manuscript. Even though I wish there were more, we have to make do with the five preludes, published on my site in the last two months.