His behaviour that last day is far from the only unanswered question about the poet's life, and having spent the last two years researching and then re-creating him for A Treacherous Likeness, I was struck how the idea of drowning had haunted Shelley, long before it claimed his own life. He'd been warned about the onset of bad weather, and when the storm came his over-rigged and unstable boat was quickly in trouble, but for some unaccountable reason he refused the help of another vessel. In July 1822, the Romantic poet Percy Bysshe Shelley went down in a storm off the Italian coast. Another finding was that a human cannot be drawn into a saltwater quicksand entirely.T his list of imaginary drownings was inspired by one of the most infamous factual ones. It increases the high viscosity regions of sediment responsible for quicksand's "trapping" power. The stability of the colloidal quicksand is changed by the presence of salt. In 2005 it was been shown that the presence of salt is important. Pressure from underground sources of water would separate and suspend the granular particles, reducing the friction between them. It was commonly believed that the behavior of quicksand was due solely to saturated or supersaturated suspensions of granules in water. The forces required to do this are quite large: to remove a foot from quicksand at a speed of one centimeter per second would require the same amount of force as "that needed to lift a medium-sized car". In order to move within the quicksand, a person or object must apply sufficient pressure on the compacted sand to re-introduce enough water to liquify it. The viscosity of the quicksand seems to increase suddenly. Around the person dense regions of sand and sediment form and grip the person. Under his weight, the person then sinks into the sol (liquidised sand). There is a sudden decrease in its viscosity. Quicksand is a non-Newtonian fluid: when undisturbed it often seems to be solid (" gel" form), but a small (less than 1%) change in the stress on the quicksand causes it to turn liquid (" sol" form). This makes it difficult to distinguish quicksand from the surrounding environment. Since the water does not usually go all the way up through the sand, the sand above does not appear to move at all, and can support leaves and other small debris. They behave more like a liquid when exposed to stress. This lubricates the sand particles and makes them unable to support any significant weight, since they move around with very little friction. The water moves up and then down slowly in a convection-like manner throughout a column of sand, and the sand remains a generally solid mass. Water circulation underground can focus in an area with just the right mixture of fine sands and other materials such as clay. Quicksand may be escaped by slow movement of the legs in order to reduce viscosity of the fluid, and rotating the body so as to float on one's back (supine). It can be difficult to get out: that is the real problem. A human or animal does not sink entirely into quicksand due to the higher density of the fluid. However, a person does not drown in quicksand. If animals or people stand on it, they sink into it. It has the characteristic of thixotropy: it looks solid, but when pressure is applied it liquifies (acts like a liquid). Quicksand is a mixture of water and sand or silt.