W was the 19th letter and was pronounced "wah"; there was an equivalent letter in the old Baybayin script of the Philippines. In the International Phonetic Alphabet, is used for the voiced labial-velar approximant. W is the symbol for the chemical element tungsten, after its German (and alternative English) name, "Wolfram". It is also the SI symbol for the watt, the standard unit of power. Double-u, whose name reflects stages in the letter's evolution when it was considered two of the same letter, a double U, is the only modern English letter whose name has more than one syllable. It is
Melting point graphically to the right, but also of Si, Ge, Ga, Bi. With extremely large changes in pressure, substantial changes to the melting point are observed. For example, the melting point of silicon at ambient pressure (0.1 MPa) is 1415 °C, but at pressures in excess of 10 GPa it decreases to 1000 °C. Melting points are often used to characterize organic and inorganic compounds and to ascertain their purity. The melting point of a pure substance is always higher and has a smaller range than the melting point of an impure substance or, more generally, of mixtures. The higher the