This demonstration shows that sand can change its characteristics when pressure is applied.
We took a surgical glove and put sand inside. In the first photo you can see the glove slump under its own weight.
Next we evacuated the glove, putting 15 pounds per square inch of pressure on the sand inside. The grains become jammed and the glove feels rock hard. It can now support it's own weight and stand on the tip of one of the fingers.
Better yet, you can deform the glove with sufficient force. If you pull hard on the fingers, they will stretch. They will keep their shape as the grains become jammed again.
The following sequence shows how we slowly let the air back in. The sand loses its solidity and returns to its fluid floppy self again.
