{MOZART'S INSTRUMENTAL MUSIC.} (28) This serenade is best known in the form of a quintet for stringed instruments, to which Mozart adapted it apparently before 1784 (506 K.). Nothing essential is altered--only the middle parts, accompaniment passages, &c., are somewhat modified. Some of the passages and movements, however, especially the andante and finale, have lost considerably by the altered tone-colouring. Various divertimenti for wind instruments, which have been published under Mozart's name, have neither external nor internal signs of authenticity.[37] An Adagio in B flat major for two clarinets and three basset-horns (411 K.), concerning which little is known, stands alone of its kind.[38] The combination of instruments points here as elsewhere (Vol. II., pp. 361, 410) to some special, perhaps masonic occasion, the more so as a detached and independent adagio could only have been written with a definite object in view. The juxtaposition of instruments so nearly related, with their full, soft, and, in their deeper notes, sepulchral tones, produces an impression of solemnity, which is in accordance with the general facter of peace after conflict expressed by the adagio. Mozart's works for wind instruments are distinguished by delicacy of treatment apart from virtuoso-like effects. Considering them, however, in the light of studies for the treatment of wind instruments as essential elements of the full orchestra, they afford no mean conception of the performances of instrumentalists from whom so much mastery of technical difficulties, delicacy of detail, and expressive delivery might be expected. Instrumental music had risen to great importance in Vienna at that time. A great number of available, and even distinguished musicians had settled there. Besides the two admirably appointed imperial orchestras, and the private bands attached to families of rank, there were various societies of musicians ready to form large or small orchestras when required; and public and private concerts were, as we have seen, of very frequent occurrence. {THE VIENNA ORCHESTRA.} (29)