Professor Hoffmann,
Modern Magic: A Practical Treatise on the Art of Conjuring
“ The loquacious gentleman is pretty sure to question the fact, or is on some pretence selected to make trial of its truth. The performer places him directly facing the audience, and after himself once more sounding the whistle, hands it to him in order to try his skill. He blows vigorously, but in vain; not a sound can he produce, but his mouth and lips gradually become obscured with a white or black dust. He finally retires to his seat amid the laughter of the audience, and generally much less disposed to make himself prominent during the remainder of the evening. ”
