Orchestration and Motives in Salome
In Salome, Strauss wrote for a 105-piece orchestra, profiting from his experience of composing symphonic poems before he got into composing operas. Over half of that large ensemble is strings, including an overpowering violin section of 16 first violins and 16 second violins. That massed violin sound is heard prominently in Salome's scene with Jochanaan's severed head. There is a large brass section (six French horns, four trumpets, four trombones and one tuba), easily able to cover most singers by themselves. Some specialized instruments include harp, celeste, xylophone, triangle, tamborine, castanets. A metal beater is to be rubbed on a gong or tam tam to depict the rushing wind that Herod hears in his madness.
There are several musical themes that have been analyzed as "leitmotifs" in Salome. I think two are the most important. The first appears when Jochanaan ascends for the first time from the cistern. It is part of the "pure" C major music associated with the Baptist (as opposed to the C# music of Salome, full of dirty little accidentals), including the striking descending tritone, resolved from D# to E at the end. Salome sings part of this theme when she sets eyes on him the first time, and it accompanies the curse that Jochanaan places on Salome as he descends again into the cistern. The sinister, deep sounds of the bass clarinet and contrabassoon are associated with the darkness of Jochanaan's prison. There is also a very unusual instrument called a heckelphone, a four-feet-long bass oboe invented by Wilhelm Heckel.
The second major theme is heard first when Salome, as she first seems repulsed by Jochanaan, sings "Er ist schreklich" (He is terrible). This triadic theme, which seems to represent her obsessive lust, sounds in the orchestra as she fantasizes about kissing parts of his body. After appearing many times through the rest of the opera, it is again prominent when Salome finally kissed Jochanaan's mouth, on his severed head.