It is understood that it is represented by a chemical formula H2O chemistry since evolved, oxygen atom and a hydrogen atom is linked covalently. Water was used as the basis of a unit of 1cal and 1kg The former (→ # chemistry).
For life of all known, water is an essential substance. Is water in the material constituting the organism, it occupies the most. It is also the most common material in the cytoplasm and nucleus, and is also used as a medium for metabolism in the cell. Normally, 70% of the organisms in the mass - 80% is occupied by water. The human body is water, about 70% from 60%.
Earth's surface, abundant in marine especially. Water is a substance necessary for the survival of the organism is familiar for human beings, but the amount that is present in a liquid state when Quick Look at the whole universe is small. About 70% of the amount of water used in the modern humanity is agricultural water. When arranged in descending order the amount of water used in the home of modern Tokyo, and a toilet, bath, and cooking. It describes the outline of the history of human knowledge about the water first, to describe the water and so understanding of modern physics followed.
Also advocated the (element) Rizomata four water, air, earth, fire, to explain the events of nature and by discrete set of it, the so-called four elements theory Empedocles of ancient Greek, [2]. This was inherited by Aristotle. Even in ancient India, thought the Great plus the sky to this earth, water, fire, wind and there has been advocated Click Here
. Also in China, the Five Elements theory that all things as consisting of five elements of wood, fire, earth, gold, water was advocated.
In other words, in all countries, that the water is than had been thought to be one of the elements of the four or five basic types, understanding of these water, among people over two thousand years or more at it has been common. It is was a very common even at the time of the late 18th century.