As far as the score of Beethoven's Missa Solemnis is concerned, it was printed by Schott in 1827 :
Symphonies with concluding chorus on Schiller's Ode: "Ode to Joy" for large orchestra, 4 Solo and 4 Chorus voices, composed and dedicated in deepest reverence to HIS MAJESTY the KING of PRUSSIA / FREDERICK WILLIAM III by Ludwig van Beethoven. 125th Work. Property of the publishers. โ Mainz and Paris, : at B. Schott's Sons. ; Antwerp (Anversa)
Meanwhile, in 1827, the individual parts were printed as follows:
Soprano / Solo, Alto / Solo, Tenor / Solo, Bass / Solo, Soprano / Chorus, Alto / Chorus, Tenor / Chorus, Violin I, Violin II, Viola, Violoncello, Bass, Organ, Flute I, Flute II, Oboe I, Oboe II, Clarinet I in A, Clarinet II in A, Bassoon I, Bassoon II, Contrabassoon, Horn I, Horn II, Horn III, Horn IV, Trumpet I, Trumpet II, Alto Trombone, Tenor Trombone, Bass Trombone, Timpani and the organ (which was not among the scores in the first edition).
So from here you can see the complete instrumentation.
Regarding the keys you are asking about:
The Credo can be divided into 4 parts:
- From Allegro ma non troppo to "descendit de coelis" in B-flat
- From "Incarnatus est" to "Resurrexit" in D
- From "Et ascendit" to the Credo in F
- The Fugue and Coda "et vitam venturi saeculi, amen" in B-flat.
Agnus Dei: Begins with the male voice in B minor and goes to D major with the "dona nobis pacem"
I hope I have clarified this for you.
But as always, for a complete description you can consult our friend Armando's website:
http://www.lvbeethov...se.html#Opus123
A warm greeting.
Luigi