Soak a thread in strong salt and water; dry thoroughly, and repeat this two or three times. This must be done privately beforehand. When you bring forward the thread thus prepared, the spectators have no reason to suppose that it is other than the ordinary article.
Use this thread to suspend a ring, choosing as light a one as possible. Set fire to the thread, which will burn from end to end, but the spectators will be surprised to see that the ring does not fall, being supported by the ash resulting from the combustion. In reality, the fibrous particles of the thread have been destroyed, but there remains a tiny filament of salt, strong enough, if there is no draught in the room, to support the weight of the ring.
This experiment may be varied in this manner:
Attach four pieces of thread to the four corners of a little piece of muslin, so as to form a miniature hammock. Soak the whole in salt water; then dry it, and repeat the operation three or four times. When the threads and the muslin are thoroughly saturated with salt and perfectly dry, place a blown egg in the little hammock, suspended as shown in the figure. Set fire to the hammock, which will burn freely enough, as also the fine threads, but if the experiment has been properly carried out, the egg will remain suspended, to the astonishment of all who behold it.
The Magic Scorpion.
Place on the surface of the water in a glass or basin a number of small pieces of camphor of various sizes, together representing the form of some animal, say a scorpion. After a little while the scorpion will begin to stir in the water; you will see him move his claws, as though trying to swim, and curl his tail convulsively, as if in pain.
This amusing experiment is easy to perform, and costs practically nothing, for camphor is to be found in every household; but in spite of its simplicity we may deduce from it, as you will see, several interesting observations.
1. Our scorpion floats on the water, but lies almost entirely below the surface. This proves to us that the specific gravity of camphor is nearly, but not quite, equal to that of water.
2. The animal does not dissolve. Camphor is therefore insoluble in water.
3. The different fragments of which our scorpion consists do not separate, but remain one against the other as we originally placed them. This is because they are held together by the force known as cohesion.