Impromptu for violin and piano (H. 166, Paris 1927) begins a new creative period in the life of Bohuslav Martinù. It consists of three short character pieces dotted with daring bitonal chords, balancing as a whole on the very edge of tonality. The author pitted the more or less diatonic violin part against the greatly dissonant piano. The piece is the first time Martinù appealed to beginning musicians, to whom he decided to give easier access to modern music. The current edition of Isa Popelka is based on the first edition of the work by Hudební matice Umelecké besedy (Prague, 1934), the Soviet edition (Moscow, 1968), and especially the composer’s manuscript housed in Policka.