Fireproof! was the slogan with which Wertheim advertised its safes. There were spectacular trials by fire. Safes were placed on large pyres; the contents survived the fire intact and could be demonstrated to the astonished crowd. In 1857 such a rehearsal took place in Constantinople in the presence of the sultan. In February 1869 the company built its 20,000th safe and commissioned Josef Strauss with the polka of the same name.