The Vanishing Knots.
For this trick you must use a silk handkerchief. Twisting it rope-fashion, and grasping it by the middle with both hands, you request one of the spectators to tie the two ends together. He does so, but you tell him he has not tied them half tight enough, and you yourself pull them still tighter. A second and a third knot are made in the same way, the handkerchief being drawn tighter by yourself after each knot is made. Finally, taking the handkerchief, and covering the knots with the loose part, you hand it to someone to hold. Breathing on it, you request him to shake out the handkerchief, when all the knots are found to have disappeared.
When the performer apparently tightens the knot, he in reality only strains one end of the handkerchief, grasping it above and below the knot. This pulls that end of the handkerchief out of its twisted condition and into a straight line, round which the other end of the handkerchief remains twisted; in other words, converts the knot into a slip-knot. After each successive knot he still straightens this same end of the handkerchief. This end, being thus made straight, would naturally be left longer than the other, which is twisted round and round it. This tendency the performer counteracts by drawing it partially back through the slip-knot at each pretended tightening. When he finally covers over the knots, which he does with the left hand, he holds the straightened portion of the handkerchief, immediately behind the knots, between the first finger and thumb of the right hand, and therewith, in the act of covering over the knots, draws this straightened portion completely out of the slip-knot.