The Sonatas in E flat major, C minor, and D minor are in N. bk. 4; E minor, C major, G major in N. bk. 5.
The so-called “Sonatas” were actually written for a Clavicembalo with two manuals and a pedal. Bach's Autograph of them belonged to his second son and an earlier copy of them to Wilhelm Friedemann. Both are now in the Berlin Royal Library. Friedemann went to Dresden as Organist in 1733 and Spitta is of opinion that the whole of the six Sonatas were in existence by or soon after 1727. If so, they must be regarded as the outcome of Bach's early years at Leipzig. See Spitta, iii. 212 ff. and Schweitzer, i. 278.
None are extant. Spitta, iii. 213 n., conjectures that Forkel refers to the Trios in D minor and C minor (N. bks. 2 p. 54, 12 p. 108) and the Pastorale in F major (N. bk. 12 p. 102.) His incomplete knowledge of the Organ works is revealed by Appendix V. infra.
This is a pure conjecture and Schweitzer scouts it (i. 416 n.).
The oldest copy of them dates from circ. 1720; they belong therefore to the late Cöthen period. The 1720 MS. is in A. M. Bach's handwriting and was discovered in 1814 at Petrograd among old papers about to be sent away to a butter dealer. The Sonatas are in P. bk. 228.
They also date from the Cöthen period and are in P. bk. 238a, 238b.
Forkel omits to mention the Brandenburg Concertos (P. bks. 261-266); the Overtures in C major (P. bk. 267), B minor (P. bk. 268), D major (P. bk. 269), D major (P. bk. 2068); and the Violin Concertos in A minor (P. bk. 229), E major (P. bk. 230), and (for two Violins) in D minor (P. bk. 231). In B.G. XXI. (1) is a Symphonic movement, in D major, for Violin and orchestra. A Sinfonia in F major (B.G. XXXI. 96) is another version of the first Brandenburg Concerto. The Clavier Concertos have been mentioned supra.
The set of five is complete only for Christmas Day, Feast of the Circumcision, Whitsunday (one of the five is of doubtful authenticity), Purification of the B.V.M., and Feast of St. Michael the Archangel. See Terry, Bach's Chorals, Part II. 2 ff.
In giving the number of Passions as five, Forkel repeats the statement of the Nekrolog. The number corresponds with the five sets of Church Cantatas which Bach is known to have written. It is, however, exceedingly doubtful whether Bach wrote more than four Passions. Only those according to St. Matthew and St. John have come down to us from C. P. E. Bach, who was left the Autographs of both by his father. The St. John Passion was first performed in 1724 and the St. Matthew Passion in 1729. Picander, Bach's librettist, certainly wrote two other Passion texts, one of which was written for Good Friday 1725, and the second, based on St. Mark's Gospel, was actually performed at St. Thomas', Leipzig, on Good Friday 1731. Spitta (ii. 505) gives good reason to hold that Bach's music for this Passion was adapted from the Trauer-Ode, which he had written in 1727 in memory of Queen Christiane Eberhardine. But of the 1725 Passion there is no trace. If it ever existed, its loss probably may be assigned to Wilhelm Friedemann's carelessness, to whom presumably it was assigned in the division of Bach's property after his death. But even so, we have no more than four Passions. There exists, however, a fifth Passion according to St. Luke, which is undoubtedly in Bach's Autograph, and which Spitta is inclined to attribute to Bach himself. It is published by Breitkopf and Haertel, but is generally regarded as being by another composer than Bach, who probably copied it for use at Leipzig. On the whole matter see Spitta, ii. 504 ff., Schweitzer, chap. xxvi., and the Bach-Jahrbuch for 1911 (Publications of the New Bachgesellschaft XII. (2)).
Other than the Passions, the only Oratorios are the Christmas Oratorio, (1734), the Easter Oratorio (c. 1736), and Ascension Oratorio (c. 1735).